Was Abraham in the New Covenant?

[brandonadams]

I hesitate to post this because I know I will get rather differing answers based upon one's understanding of the New Covenant (specifically, are all in the New Covenant elect), but I will ask anyways. (If you could note in your reply first if you believe all in the New Covenant are elect or not, that may help avoid confusion):

I have always understood that the saints of the Old Testament were members of the New Covenant. Just as Christ's cross work reaches back in time, so does the New Covenant. In fact, I would say because the cross reaches back in history, so must the New Covenant. For the blood of Christ is the blood of the New Covenant, not the blood of any other covenant. Christ is the High Priest of the New Covenant and not of any other. Thus for anyone to benefit from His sacrifice to the Father, they must be in the New Covenant.

Also, I don't think I see any other covenants promising a new heart and complete forgiveness of sins. So anyone who has the law re-written on their new heart, and who's sins are remembered no more, in my mind, must be a member of the New Covenant.

I have not seen very much written on this at all. Most writers seem to assume he could not be, I think because they believe it was not yet inaugurated (Samuel Waldron makes this point specifically in his Exposition of LBC). But I have seen very little argumentation on this, mostly assumption. Likewise, Nehemia Coxe seems to assume that Abraham was in the New Covenant, as he makes passing reference to it in his work, yet it seems he also just assumes this without defending or arguing for it.

Any thoughts would be appreciated, thanks.

 

[Semper Fidelis]

I think O. Palmer Robertson offers a great way of looking at the unfolding of the Covenant of Grace in this book: Christ of the Covenants He calls the Abrahamic Covenant the Covenant of Promise. It is related to the New Covenant in that Abraham participated in the substance of what was fulfilled in the New Covenant but he didn't participate in the New Covenant per se.

 

[ChristianTrader]

Didn't O. Palmer Robertson write Christ of the Covenants?

 

[SolaScriptura]

I think Owen Anderson offers a great way of looking at the unfolding of the Covenant of Grace in Christ of the Covenants. He calls the Abrahamic Covenant the Covenant of Promise. It is related to the New Covenant in that Abraham participated in the substance of what was fulfilled in the New Covenant but he didn't participate in the New Covenant per se.

I agree with this position... but to whom are you referring? To Owen Anderson, professor at Arizona State, or to O. Palmer Robertson, author of Christ of the Covenants?

 

[Semper Fidelis]

I'm sorry, I meant O. Palmer Roberston. I wrote that in haste as I was running off to do something else.

 

[Semper Fidelis]

Calvin gives a masterful presentation of the similiarities between the Covenants (that the OT Saints were not pursuing works but Christ) in Chapter 10 of Book II of the Institutes: Calvin's Institutes Book 2, Chapter 10

The differences between the Covenants are expressed well in Chapter 11: Calvin's Institutes Book 2, Chapter 11. I really like this presentation:

Section 6. Notwithstanding, among those under the Law, some of the strongest examples of faith are exhibited, their equals being scarcely to be found in the Christian Church. The ordinary method of the divine dispensation to be here attended to. These excellent individuals placed under the Law, and aided by ceremonies, that they might behold and hail Christ afar off.

There is nothing contrary to this in the fact, that in the Christian Church scarcely one is to be found who, in excellence of faith, can be compared to Abraham, and that the Prophets were so distinguished by the power of the Spirit, that even in the present day they give light to the whole world. For the question here is, not what grace the Lord conferred upon a few, but what was the ordinary method which he followed in teaching the people, and which even was employed in the case of those very prophets who were endued with special knowledge above others. For their preaching was both obscure as relating to distant objects, and was included in types. Moreover, however wonderful the knowledge displayed in them, as they were under the necessity of submitting to the tutelage common to all the people, they must also be ranked among children. Lastly, none of them ever had such a degree of discernment as not to savour somewhat of the obscurity of the age. Whence the words of our Saviour, "Many kings and prophets have desired to see the things which you see, and have not seen them, and to hear the things which ye hear, and have not heard them. Blessed are your eyes, for they see, and your ears, for they hear," (Mat 13: 17). And it was right that the presence of Christ should have this distinguishing feature, that by means of it the revelation of heavenly mysteries should be made more transparent. To the same effect is the passage which we formerly quoted from the First Epistle of Peter, that to them it was revealed that their labour should be useful not so much to themselves as to our age.

Dispensational thinking, in fact, has tended to look at the Law as a step backward in the Covenant of Grace and that Israel should have rejected the Law in favor of the unilateral Promise given Abraham. Viewed properly as an unfolding and a period of immaturity, there is a progression.

I like the way O. Palmer Robertson puts it. In effect he states that the Covenant of Promise might be seen as a period of infancy in the CoG and the Law as a period of adolescence with further progress in the unfolding of the Kingdom and then the fulfillment and maturity in the NC.

It is sometimes easy to look at the simplicity of the Covenant of Promise under Abraham and see his amazing faith but then compare it with the messiness of the Law and later things and conclude that a step back has occurred but, in fact, it's like comparing infancy with adolescence. Parents understand that adolescence is a preferable stage in maturity than remaining an infant but, while you're in the middle of it, one might long for the days when things were a bit simpler than the turmoil of the adolescent years.

The Covenant of Grace progresses inexorably according to God's plan and unfolding and not in fits and starts and it's helpful to realize that Abraham is the father of our faith but, as above, was disadvantaged compared to the light we have.

 

[Herald]

I think O. Palmer Robertson offers a great way of looking at the unfolding of the Covenant of Grace in this book: Christ of the Covenants He calls the Abrahamic Covenant the Covenant of Promise. It is related to the New Covenant in that Abraham participated in the substance of what was fulfilled in the New Covenant but he didn't participate in the New Covenant per se.

Even a Baptist can agree with that!

 

[Blueridge Believer]

Jhn 8:56 Your father Abraham rejoiced to see my day: and he saw [it], and was glad.

Yes Abraham was in the New Covenant:



Rom 4:1 What shall we say then that Abraham our father, as pertaining to the flesh, hath found?
Rom 4:2 For if Abraham were justified by works, he hath [whereof] to glory; but not before God.
Rom 4:3 For what saith the scripture? Abraham believed God, and it was counted unto him for righteousness.
Rom 4:4 Now to him that worketh is the reward not reckoned of grace, but of debt.
Rom 4:5 But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.
Rom 4:6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,
Rom 4:7 [Saying], Blessed [are] they whose iniquities are forgiven, and whose sins are covered.
Rom 4:8 Blessed [is] the man to whom the Lord will not impute sin.
Rom 4:9 [Cometh] this blessedness then upon the circumcision [only], or upon the uncircumcision also? for we say that faith was reckoned to Abraham for righteousness.
Rom 4:10 How was it then reckoned? when he was in circumcision, or in uncircumcision? Not in circumcision, but in uncircumcision.
Rom 4:11 And he received the sign of circumcision, a seal of the righteousness of the faith which [he had yet] being uncircumcised: that he might be the father of all them that believe, though they be not circumcised; that righteousness might be imputed unto them also:
Rom 4:12 And the father of circumcision to them who are not of the circumcision only, but who also walk in the steps of that faith of our father Abraham, which [he had] being [yet] uncircumcised.
Rom 4:13 For the promise, that he should be the heir of the world, [was] not to Abraham, or to his seed, through the law, but through the righteousness of faith.
Rom 4:14 For if they which are of the law [be] heirs, faith is made void, and the promise made of none effect:
Rom 4:15 Because the law worketh wrath: for where no law is, [there is] no transgression.
Rom 4:16 Therefore [it is] of faith, that [it might be] by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,
Rom 4:17 (As it is written, I have made thee a father of many nations,) before him whom he believed, [even] God, who quickeneth the dead, and calleth those things which be not as though they were.
Rom 4:18 Who against hope believed in hope, that he might become the father of many nations, according to that which was spoken, So shall thy seed be.
Rom 4:19 And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sara's womb:
Rom 4:20 He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God;
Rom 4:21 And being fully persuaded that, what he had promised, he was able also to perform.
Rom 4:22 And therefore it was imputed to him for righteousness.
Rom 4:23 Now it was not written for his sake alone, that it was imputed to him;
Rom 4:24 But for us also, to whom it shall be imputed, if we believe on him that raised up Jesus our Lord from the dead;
Rom 4:25 Who was delivered for our offences, and was raised again for our justification.

-----Added 3/9/2009 at 03:19:04 EST-----

According to Gal. 3:8 Abraham had the Gospel preached unto him. He believed it so that would put him into the covenant:

Gal 3:7 Know ye therefore that they which are of faith, the same are the children of Abraham.
Gal 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, [saying], In thee shall all nations be blessed.
Gal 3:9 So then they which be of faith are blessed with faithful Abraham.

 

[dbroyles]

I think we can safely say that Abraham was in Christ who was the Substance of the Old Covenant as well as the New.

 

[brandonadams]

the similiarities between the Covenants (that the OT Saints were not pursuing works but Christ)

I have trouble with that kind of reasoning. Just because all OT saints were saved by faith alone does not mean that the Covenants are therefore similar. The logic seems to go like this, correct me if I'm wrong:

P1: Abraham was in the Abrahamic Covenant
P2: Abraham was saved (elect)
C: Therefore the Abrahamic Covenant saved Abraham

Am I missing a step? Because that does follow for me.

It seems to me that a lot of confusion is introduced by the idea that every covenant must be about eternal salvation or eternal damnation, when to me it seems clear that not every covenant is. The promise that the Savior of the world will physically descend from you is not the same thing as the promise that you will be saved from hell. (And I would say what saved Abraham was the belief that Christ would bless all the nations of the world, rather than the belief that Abraham would come from him)

 

[BG]

Brandon, do you believe that the Abrahamic covenant is a covenant of grace (God is Promising to die for his sins ( and his children))? Or, do you believe that the Abrahamic covenant is a physical covenant?

 

[brandonadams]

Good question Bill. I think I would say that the Abrahamic Covenant was a prophecy of the Covenant of Grace and that it was a physical covenant that this Redeemer would come from Abraham.

 

[dbroyles]

the similiarities between the Covenants (that the OT Saints were not pursuing works but Christ)

I have trouble with that kind of reasoning. Just because all OT saints were saved by faith alone does not mean that the Covenants are therefore similar. The logic seems to go like this, correct me if I'm wrong:

P1: Abraham was in the Abrahamic Covenant
P2: Abraham was saved (elect)
C: Therefore the Abrahamic Covenant saved Abraham

Am I missing a step? Because that does follow for me.

It seems to me that a lot of confusion is introduced by the idea that every covenant must be about eternal salvation or eternal damnation, when to me it seems clear that not every covenant is. The promise that the Savior of the world will physically descend from you is not the same thing as the promise that you will be saved from hell. (And I would say what saved Abraham was the belief that Christ would bless all the nations of the world, rather than the belief that Abraham would come from him)

The covenants are not identical, but the foundation is the same -- Jesus Christ. Salvation must be in view when Paul quotes Gen. 12:3 "In thee shall all the nations of the earth be blessed" in Gal. 3:6-9. He clarifies that those of faith are "with" Abraham as recipients of the blessing of justification, resulting from an imputed righteousness. At least from this passage we could say,

P1: The spiritual benefit of the Abrahamic Covenant was justification by Christ.
P2: Abraham received the spiritual benefit of the Abrahamic Covenant.
C: Therefore, Abraham was justified by Christ.

 

[brandonadams]

Thanks David. I appreciate the clarification, but I'm not sure I agree with your syllogism. P1 is what we are trying to discern. Your conclusion is something we already agree on, so it seems a bit backwards to me.

 

[dbroyles]

Thanks David. I appreciate the clarification, but I'm not sure I agree with your syllogism. P1 is what we are trying to discern. Your conclusion is something we already agree on, so it seems a bit backwards to me.

Brandon,

You're welcome.

Hmm. The syllogism is sound if my first proposition is true.

Our only debate is whether under the Abrahamic Administration there was saving faith that resulted in imputed righteousness.

I think you have a good point regarding the blood of the New Covenant. Imputed righteousness could not happen apart from the benefits obtained under the New Covenant, so there is an important connection. But I think we have to see that they ARE connected. Else how could Paul say that "those of faith are the sons of Abraham"? Otherwise no spiritual benefit could be obtained. Ps. 108:8-10 celebrates God's covenant faithfulness to Abraham where "the thousand generations" implies eternality.

My point is that you are correct in the sense that the accomplishment of Christ's work in the New Covenant is effectual for all of the elect. But it is also correct to say that saving benefits were part of the Old Covenant, even as they pointed forward to and were fulfilled in Christ the Substance. If not, then it makes no sense for the Scriptures to say that the gospel was preached to Abraham in the Abrahamic Covenant (Gal. 3:8).

 

[Contra_Mundum]

Note also, Gal.3:19 says the Law was ADDED. Added to what? And has that Law been subtracted again? That seems to be Paul's argument.

Ergo, the substance (Christ) remains the same from Abraham to and through Christ. The "New" Covenant is new relative to the "Old" Covenant--which is Moses, and which is NOT everything prior to Christ's incarnation and death/burial/resurrection. Otherwise, again Paul's argument loses its main punch.

So, it is a bit anachronistic to speak in terms of Abraham being "in" the New Covenant, since properly speaking the New Covenant is the Christic Administration of the Covenant of Grace. However, in the sense that there is that intervening (Old) administration with the legal "additions" that served in its own era but which glory fades away (see 2Cor.3:13ff), the simplicity that was more evident in Abraham's era is renewed in the latter age. Only with new advantages appropriate to this era of fulfillment.

 

[moral necessity]

Abraham was in the "new" Covenant. I believe that he represented it, yet it was not necesarrily portrayed in it's full form from his generation onward. I think there is some overlap between the new and the old within himself and within his offspring, in that it was not present within many of those afterwards quite like it was present within those before. Many of his offspring later were compelled to follow Moses, and the Law that was given to the Israelites at that time, which truly endowed much of God's moral will, as well as his will with how to govern a nation and for how to sacrafice as a covenantal people. But, throughout it all, I think that many experienced the New Covenant promises given to Abraham as they overlapped from the Jewish nation era. And, as that Jewish nation diminished, the line of Abraham did not.

Blessings!

 

[BG]

the similiarities between the Covenants (that the OT Saints were not pursuing works but Christ)

I have trouble with that kind of reasoning. Just because all OT saints were saved by faith alone does not mean that the Covenants are therefore similar. The logic seems to go like this, correct me if I'm wrong:

P1: Abraham was in the Abrahamic Covenant
P2: Abraham was saved (elect)
C: Therefore the Abrahamic Covenant saved Abraham

Am I missing a step? Because that does follow for me.

It seems to me that a lot of confusion is introduced by the idea that every covenant must be about eternal salvation or eternal damnation, when to me it seems clear that not every covenant is. The promise that the Savior of the world will physically descend from you is not the same thing as the promise that you will be saved from hell. (And I would say what saved Abraham was the belief that Christ would bless all the nations of the world, rather than the belief that Abraham would come from him)

Brandon, I thought that I would point out a couple of things.
We both agree that it was promised to Abraham, that through his descendants the Christ would come (ch 12 All of the families of the earth would be blessed,).

I believe that in ch15 there is a salvific promise made to Abraham. In this chapter God comes to Abraham to make the Covenant with him. He tells him to cut up the animals, place them in two lines and then a most amazing thing happens. Rather than God passing through and then Abraham. God passes through twice. There are two interesting things happening here one is this: the two parties that swear an oath here are not God and Abraham but God and God. If I might paraphrase here, God is swearing an oath to Abraham that if He does not keep his end of the Covenant may what has happened to the animals happen to Him. And then He says Abraham if you can't keep your end of the Covenant (and he could not) I swear an oath to you that I will do it for you. In my opinion this is a salvific Covenant.

In ch 17 we see God again talking about his covenant with Abraham, " I will establish my covenant between me and you and your offspring after you throughout their generations for an everlasting covenant, to be God to you and to your offspring after you. And I will give to you and to your offspring after you the land of your sojournings, all the land of canaan for an everlasting possession, and I will be their God." Here we see both aspects of the covenant. One there is a physical side and two a salvific. If that were not so the parts in red above, would be meaningless. Would you agree?

 

[brandonadams]

The "New" Covenant is new relative to the "Old" Covenant--which is Moses, and which is NOT everything prior to Christ's incarnation and death/burial/resurrection.

Thanks Bruce, that is helpful. I have some more thinking to do.

Here we see both aspects of the covenant. One there is a physical side and two a salvific. If that were not so the parts in red above, would be meaningless. Would you agree?

Well, what you highlighted in red can be understood in more than one way. God was the God of the Israelites, but not every Israelite was saved. He was their God in the sense that He related to them in a way that He did not relate to the rest of the nations. So "I will be their God" does not always mean "I will save them eternally."

However, yes, clearly there is a twofold element here. I'm having a difficult time discerning that aspect of it I suppose. To me it still makes sense to say that the Abrahamic Covenant prophesied the New Covenant, which is salvation.

 

[Semper Fidelis]

Brandon,

One of the things to consider is how Calvin speaks of the physical above.

I think many of us are latent gnostics in our approach to the created order and tend to default to the idea that the physical is bad.

One of the things that Palmer Robertson says that I like to repeat is that, in circumcising the family of Abraham it was a signification of the reverse of the effects of the Fall. A family was brought into Covenant with God. God didn't pit grace against the created order but against sin. Grace is restorative of all relationships and, it is no wonder then, that one of the prophesis of John the Baptist at the end of the Old Covenant is that the hearts of father and son would be restored to one another.

Of course salvation is more than physical blessing but it is not an either/or. It is not either physical or salvific but salvation is signified by God acting on a people. Were it not for God acting in these historical ways to defeat armies, to part seas, to feed millions, to give water from the Rock, then the revelation of God's character would not be complete. It is in the doing of these things that God reveals Himself.

In fact, then, it is God even taking on human flesh that He comes closest to us and reveals Himself to us. Without the veil of Christ's flesh, we would be unable to approach God not only for reconciliation but for revelation but God would be hidden in a fiery cloud in Holiness unapproachable.

My point to all this is that we have to be careful not to pit physical against spiritual and carve up Abraham's blessing because we miss out on a clear understanding of redemption when we divorce God's blessing from the history of that blessing.

 

[Knoxienne]

Brandon,

One of the things to consider is how Calvin speaks of the physical above.

I think many of us are latent gnostics in our approach to the created order and tend to default to the idea that the physical is bad.

One of the things that Palmer Robertson says that I like to repeat is that, in circumcising the family of Abraham it was a signification of the reverse of the effects of the Fall. A family was brought into Covenant with God. God didn't pit grace against the created order but against sin. Grace is restorative of all relationships and, it is no wonder then, that one of the prophesis of John the Baptist at the end of the Old Covenant is that the hearts of father and son would be restored to one another.

Of course salvation is more than physical blessing but it is not an either/or. It is not either physical or salvific but salvation is signified by God acting on a people. Were it not for God acting in these historical ways to defeat armies, to part seas, to feed millions, to give water from the Rock, then the revelation of God's character would not be complete. It is in the doing of these things that God reveals Himself.

In fact, then, it is God even taking on human flesh that He comes closest to us and reveals Himself to us. Without the veil of Christ's flesh, we would be unable to approach God not only for reconciliation but for revelation but God would be hidden in a fiery cloud in Holiness unapproachable.

My point to all this is that we have to be careful not to dichotomize physical and spiritual and carve up Abraham's blessing because we miss out on a clear understanding of redemption when we divorce God's blessing from the history of that blessing.

Excellent perspective.

 

[brandonadams]

My point to all this is that we have to be careful not to pit physical against spiritual and carve up Abraham's blessing because we miss out on a clear understanding of redemption when we divorce God's blessing from the history of that blessing.

I appreciate your thoughts Rich. However, my concern is not so much with carving up the physical from the spiritual, but rather distinguishing the type from the antitype. I have been rather confused by the blending of the two in things I have read on the covenants.

 

[Ronnie]

What helps to untangle this knot is to understand the distinctions that are made when speaking of the covenants. There is only one covenant of Grace, but there are multiple administrations of this one Covenant. The Abrahamic Covenant and the New Covenant are therefore both administrations of the covenant of the Grace. Abraham was not under the administration of the New Covenant, but he was a member of the covenant of Grace with all elect.

 

[brandonadams]

Thanks for your input Ronnie. However, that explanation actually does not help untangle any knots in my mind. Though Owen was speaking of the Mosaic vs. the New, I agree when he says:

“wherefore we must grant two distinct covenants, rather than a twofold administration of the same covenant merely, to be intended”
http://michaelbrown.squarespace.com/the-latest-post/2007/12/29/owen-on-the-mosaic-covenant.html

-----Added 3/27/2009 at 12:47:11 EST-----

Ergo, the substance (Christ) remains the same from Abraham to and through Christ. The "New" Covenant is new relative to the "Old" Covenant--which is Moses, and which is NOT everything prior to Christ's incarnation and death/burial/resurrection. Otherwise, again Paul's argument loses its main punch.

Bruce, in order to better understand you - when you say this, do you mean that Jeremiah 31:31-33 describes the Abrahamic Covenant, and that the "new" language is simply used to contrast it with the Mosaic? That appears to be what Witsius is saying in the quote below:

Nor Formally the Covenant of Grace: “Because that requires not only obedience, but also promises, and bestows strength to obey. For, thus the covenant of grace is made known, Jer. xxxii. 39. ‘and I will give them one heart, and one way, that they may fear me for ever.’ But such a promise appears not in the covenant made at mount Sinai. Nay; God, on this very account, distinguishes the new covenant of grace from the Sinaitic, Jer. xxxi. 31-33. And Moses loudly proclaims, Deut xxix. 4. ‘yet the Lord hath not given you a heart to perceive, and eyes to see, and ears to hear, unto this day.’ Certainly, the chosen from among Israel had obtained this. Yet not in virtue of this covenant, which stipulated obedience, but gave no power for it: but in virtue of the covenant of grace, which also belonged to them.”

Witsius on the Mosaic Covenant: Works or Grace? reformed blogging.

 

[Ronnie]

Thanks for your input Ronnie. However, that explanation actually does not help untangle any knots in my mind. Though Owen was speaking of the Mosaic vs. the New, I agree when he says:

“wherefore we must grant two distinct covenants, rather than a twofold administration of the same covenant merely, to be intended”
pilgrim people-Christ urc-reformed - the latest post - Owen on the MosaicCovenant

Brandon,

The Mosaic Covenant is different from the Abrahamic Covenant. You originally asked about the Abrahamic Covenant and my comments were in response to that. The Mosaic Covenant is a bit more complicated because it has a work principle in it, which is what Owens was getting at when he said it was a distinct covenant from the Covenant of Grace that is found in both Abrahamic and New Covenant.

 

[Contra_Mundum]

Brandon,
To your question: in short, yes. I think Jeremiah understands that the covenant with Abraham is one that entails an everlasting fulfillment. Later covenants are means to that end, but as Paul says, they cannot disannul anything God has made promissory, which he ratified by his unilateral "walking through the pieces". Later covenants may have peculiar, subsidiary ends of their own, but those purposes in the end serve the greater.

The new covenant to come (relative to Jeremiah) is in fulfillment of God's promise to Abraham. It is designed to do its job superior to Moses', because it will have additional, Spiritual power. The Messiah's arrival and accomplishment will be the demonstration of its final sufficiency.

Here is a way to consider the previous matter from a future orientation: When the cosmos is renovated, in a totally renewed creation, in new bodies, in an entirely new way of existence which we cannot even conceive this side of heaven, there will be "new" arrangements. How will we worship God THEN? Similarly to now, but also differently; I just know he will explain it fully for us then, because when we no longer "hope" for what we "have" we are going to need new directions.

But our Mediator will not change, the sacrificial basis for our acceptance will not move. Portions of Spirit-reality that were established eternally while yet in this frame (some of which are as old as the proto-evangelium (Gen3:15) are not going to be shaken. But as worship will have to change/adjust (as in past ages), so to there will have to be an administration of the covenant suitable for the eternal state.

In principle, yes, all things have become new, Paul says, because of the ordination of the Mediator. But because we are "already/not yet", all things in toto have not "become new" according to their final arrangements.

This is the manner in which I understand Abraham's covenant has seen (and continues to see) progressive fulfillment. This is generally what we mean when we speak of one covenant of grace, with different administrations.

 

[lshepler412]

I hesitate to post this because I know I will get rather differing answers based upon one's understanding of the New Covenant (specifically, are all in the New Covenant elect), but I will ask anyways. (If you could note in your reply first if you believe all in the New Covenant are elect or not, that may help avoid confusion):

I have always understood that the saints of the Old Testament were members of the New Covenant. Just as Christ's cross work reaches back in time, so does the New Covenant. In fact, I would say because the cross reaches back in history, so must the New Covenant. For the blood of Christ is the blood of the New Covenant, not the blood of any other covenant. Christ is the High Priest of the New Covenant and not of any other. Thus for anyone to benefit from His sacrifice to the Father, they must be in the New Covenant.

Also, I don't think I see any other covenants promising a new heart and complete forgiveness of sins. So anyone who has the law re-written on their new heart, and who's sins are remembered no more, in my mind, must be a member of the New Covenant.

I have not seen very much written on this at all. Most writers seem to assume he could not be, I think because they believe it was not yet inaugurated (Samuel Waldron makes this point specifically in his Exposition of LBC). But I have seen very little argumentation on this, mostly assumption. Likewise, Nehemia Coxe seems to assume that Abraham was in the New Covenant, as he makes passing reference to it in his work, yet it seems he also just assumes this without defending or arguing for it.

Any thoughts would be appreciated, thanks.

Here are a few questions from the Westminster Children's Catechism that offer a basic explanation:

Q. 61. How were pious persons saved before the coming of Christ?
A. By believing in a Savior to come.

Q. 62. How did they show their faith?
A. By offering sacrifices on God's altar

God made the covenant of works with Adam, Adam didn't keep it and sinned against God. Adam represented all of mankind. So all are sinners.

God made the covenant of grace with Christ.

All the elect, including Abraham are under the covenant of grace

Q. 43. With whom did God the Father make the covenant of grace?
A. With Christ, his eternal Son.

Q. 44. Whom did Christ represent in the covenant of grace?
A. His elect people.

Q. 45. What did Christ undertake in the covenant of grace?
A. To keep the whole law for his people, and to suffer the punishment due to their sins