I would like to have some input and add some questions here based upon a look at Genesis 17 and Romans 4. But I have been sick the last few days. I will say that I do not believe the Abrahamic is strickly the Covenant of Grace. But I don't have the mental powers or fortitude to partake yet. Give me a few days to recover. I have been running a fever the last few days. While you asking who is the mediator of the Abrahamic go on to ask who is the mediator of the others. Starting with the Covenant of Redemption and the Covenant of Works. Then move on down to the Noahic, Mosaic, Davidic, and so on.
I do believe the Abrahamic does administer the CofG but it also has elements of the CofW. As does the Mosaic.
This is something I have been thinking about recently.
There are some who would see the Abrahamic covenant as purely gracious or a gospel covenant and the Mosaic as a re-publication of the CoW or a law covenant. As I have been reading through these covenants again I would say I do see them both mixing the elements of law and gospel.
In the Abrahamic Covenant there is no doubt grace is present and yet God reminds Abraham to walk before him and be blameless. In the Mosaic Covenant we see that it is based on the covenant with Abraham but to a large degree it is a, ‘this do and live’ covenant. However would it be correct to say there is more grace than law in the Abrahamic covenant and perhaps a greater emphasis on law than grace in the Mosaic Covenant?
The problem in your thinking is the radical disjunction between law and gospel. The Biblical distinction is between guilt and grace, never obedience and faith. You seem to think that the Abrahamic, or Mosaic, covenant is not completely a part of the cov of grace, because demands were put upon them. But then you must be forced to think the same thing of the New Covenant, for it places demands upon us. Consider these words of Jesus, and think if you ought not rethink your radical formulation of law/gospel antithesis.
Matt 7:21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father who is in heaven.
Matt. 7:22 Many will say to me in that day, Lord, Lord, did we not prophesy by thy name, and by thy name cast out demons, and by thy name do many mighty works?
Matt. 7:23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
Matt. 7:24 Every one therefore that heareth these words of mine, and doeth them, shall be likened unto a wise man, who built his house upon the rock:
Matt. 7:25 and the rain descended, and the floods came, and the winds blew, and beat upon that house; and if fell not: for it was founded upon the rock.
Matt. 7:26 And every one that heareth these words of mine, and doeth them not, shall be likened unto a foolish man, who built his house upon the sand:
Matt. 7:27 and the rain descended, and the floods came, and the winds blew, and smote upon that house; and it fell: and great was the fall thereof.
Clearly here Christ teaches that those who will be saved are those that hear his words and doeth them. Does this deny justification by faith? Not at all. Rather it teaches that those who have faith obey. God has joined faith and obedience together. We can distinguish between the two, but they cannot be separated. Going back to the original question about Abraham and Moses; God called his people to have faith, and therefore obedience. Likewise in the New Covenant God calls his people to have faith, and therefore obedience. There is no difference between the New Covenants and the previous covenants, in this respect. You need to stop thinking that everything that places demands upon men is part of law and opposed to the gospel. The gospel places demands upon us. The gospel calls men to faith, and faith necessitates obedience. Instead, we ought to think of a guilt/grace paradigm. All men are guilty before God, but God in his grace saves us from our guilt and misery. But God saves and calls us unto good works.
Eph. 2:8 for by grace have ye been saved through faith; and that not of yourselves, it is the gift of God;
Eph. 2:9 not of works, that no man should glory.
Eph. 2:10 For we are his workmanship, created in Christ Jesus for good works, which God afore prepared that we should walk in them.
Rev. 21:7 He that overcometh shall inherit these things; and I will be his God, and he shall be my son.
Rev. 21:8 But for the fearful, and unbelieving, and abominable, and murderers, and fornicators, and sorcerers, and idolaters, and all liars, their part shall be in the lake that burneth with fire and brimstone; which is the second death.
Heb. 12:12 Wherefore lift up the hands that hang down, and the palsied knees;
Heb. 12:13 and make straight paths for your feet, that that which is lame be not turned out of the way, but rather be healed.
Heb. 12:14 Follow after peace with all men, and the sanctification without which no man shall see the Lord:
Heb. 12:15 looking carefully lest there be any man that falleth short of the grace of God; lest any root of bitterness springing up trouble you, and thereby the many be defiled;
Heb. 12:16 lest there be any fornication, or profane person, as Esau, who for one mess of meat sold his own birthright.
Heb. 12:17 For ye know that even when he afterward desired to inherit the blessing, he was rejected; for he found no place for a change of mind in his father, though he sought is diligently with tears.
James 2:14 What doth it profit, my brethren, if a man say he hath faith, but have not works? can that faith save him?
James 2:15 If a brother or sister be naked and in lack of daily food,
James 2:16 and one of you say unto them, Go in peace, be ye warmed and filled; and yet ye give them not the things needful to the body; what doth it profit?
James 2:17 Even so faith, if it have not works, is dead in itself.
James 2:18 Yea, a man will say, Thou hast faith, and I have works: show me thy faith apart from thy works, and I by my works will show thee my faith.
James 2:19 Thou believest that God is one; thou doest well: the demons also believe, and shudder.
James 2:20 But wilt thou know, O vain man, that faith apart from works is barren?
James 2:21 Was not Abraham our father justified by works, in that he offered up Isaac his son upon the altar?
James 2:22 Thou seest that faith wrought with his works, and by works was faith made perfect;
James 2:23 and the scripture was fulfilled which saith, And Abraham believed God, and it was reckoned unto him for righteousness; and he was called the friend of God.
James 2:24 Ye see that by works a man is justified, and not only by faith.
James 2:25 And in like manner was not also Rahab the harlot justified by works, in that she received the messengers, and sent them out another way?
James 2:26 For as the body apart from the spirit is dead, even so faith apart from works is dead.