Chap 18 on Assurance in both WCF and LBCF

If I understand your question properly, the answer is NO. From all that I have read the conclusion I have drawn is that all believers may attain unto full assurance, but that some, perhaps many do not.

Westminster Shorter Catechism
QUEST. XXXVI. WHAT are the benefits which flow from sanctification?
ANS. Assurance of God’s love, peace of conscience, joy in the Holy Ghost, increase of grace, and perseverance therein to the end.

The first benefit flowing from sanctification, is assurance of God’s love.
2 Pet. 1:10., “Give diligence to make your calling and election sure.” Sanctification is the seed, assurance is the flower which grows out of it: assurance is a consequent of sanctification, the saints of old had it, 1 John 2:3., “We know that we know him,” 2 Tim. 1:12, “I know whom I have believed,”—here was sensus fides,—the reflex act of faith; and Gal. 2:20., “Christ hath loved me,”—here was faith flourishing into assurance. Æcolampadias, when he was sick, pointed to his heart, saying, Hic sat lucis,—‘Here I have light enough,’ meaning comfort and assurance.

QUEST. 1. Have all sanctified persons assurance? [from Watson]
Ans. They have a right to it, and I do incline to believe that all have it in some degree before their last expiring; though their comfort may not be so strong, and their vital spirits so weak, that they cannot express what they feel. But I dare not positively affirm that all have assurance in the first moment of their sanctification; a letter may be written, when it is not sealed,—so grace may be written in the heart, yet the Spirit may not set the seal of assurance to it. God is a free agent, and may give or suspend assurance pro licito as he pleases. Where there is the sanctifying work of the Spirit, he may withhold the sealing work, partly to keep the soul humble, partly to punish our careless walking; we neglect our spiritual watch, grow remiss in duty, and then walk under a cloud; we quench the graces of the Spirit, and God withholds the comforts: and partly to put a difference between earth and heaven. This I the rather speak, to bear up the hearts of God’s people who are dejected because they have no assurance; you may have the water of the Spirit poured on you in sanctification, though not the oil of gladness in assurance; there may be faith of adherence, and not of evidence; there may be life in the root, when there is no fruit in the branches to be seen; so faith in the heart, when no fruit of assurance.

Watson, T. (1855). The Select Works of the Rev. Thomas Watson, Comprising His Celebrated Body of Divinity, in a Series of Lectures on the Shorter Catechism, and Various Sermons and Treatises (p. 167). New York: Robert Carter & Brothers.
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Westminster Confession of Faith
CHAPTER XVIII. Of Assurance of Grace and Salvation

III. This infallible assurance doth not so belong to the essence of faith, but that a true believer may wait long, and conflict with many difficulties, before he be partaker of it:k yet, being enabled by the Spirit to know the things which are freely given him of God, he may, without extraordinary revelation, in the right use of ordinary means, attain there unto.l And therefore it is the duty of every one to give all diligence to make his calling and election sure;m that thereby his heart may be enlarged in peace and joy in the Holy Ghost, in love and thankfulness to God, and in strength and cheerfulness in the duties of obedience,n the proper fruits of this assurance: so far is it from inclining men to looseness.o

k 1 John 5:13. These things have I written unto you that believe on the name of the Son of God, that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. Isa. 1:10. Who is among you that feareth the Lord, that obeyeth the voice of his servant, that walketh in darkness, and hath no light? let him trust in the name of the Lord, and stay upon his God. Mark 9:24. And straightway the father of the child cried out, and said with tears, Lord, I believe; help thou mine unbelief. [See Psal. 88 throughout. Psal. 77 to the 12th Verse.]

l 1 Cor. 2:12. Now we have received not the Spirit of the world, but the Spirit which is of God; that we might know the things that are freely given to us of God. 1 John 4:13. Hereby know we that we dwell in him, and he in us, because he hath given us of his Spirit. Heb. 6:11. And we desire that every one of you do show the same diligence, to the full assurance of hope unto the end: Ver. 12. That ye be not slothful, but followers of them, who, through faith and patience, inherit the promises. Eph. 3:17. That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love, Ver. 18. May be able to comprehend with all saints, what is the breadth, and length, and depth, and height; Ver. 19. And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God.

m 2 Pet. 1:10. Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things ye shall never fall.

n Rom. 5:1. Therefore being justified by faith, we have peace with God through our Lord Jesus Christ: Ver. 2. By whom also we have access by faith into this grace wherein we stand, and rejoice in hope of the glory of God. Ver. 5. And hope maketh not ashamed; because the love of God is shed abroad in our hearts by the Holy Ghost, which is given unto us. Rom. 14:17. For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost. Rom. 15:13. Now, the God of hope fill you with all joy and peace in believing, that ye may abound in hope, through the power of the Holy Ghost. Eph. 1:3. Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ: Ver. 4. According as he hath chosen us in him before the foundation of the world, that we should be holy, and without blame before him in love. Psal. 4:6. There be many that say, Who will show us any good? Lord, lift thou up the light of thy countenance upon us. Ver. 7. Thou hast put gladness in my heart, more than in the time that their corn and their wine increased. Psal. 119:32. I will run the way of thy commandments, when thou shalt enlarge my heart.

o 1 John 2:1. My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous. Ver. 2. And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world. Rom. 6:1. What shall we say then? shall we continue in sin, that grace may abound? Ver. 2. God forbid: how shall we that are dead to sin live any longer therein? Tit. 2:11. For the grace of God that bringeth salvation hath appeared to all men; Ver. 12. Teaching us, that denying ungodliness and worldly lusts, we should live soberly, righteously, and godly, in this present world. Ver. 14. Who gave himself for us, that he might redeem us from all iniquity, and purify unto himself a peculiar people, zealous of good works. 2 Cor. 7:1. Having therefore these promises, dearly beloved, let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God. Rom. 8:1. There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit. Ver. 12. Therefore, brethren, we are debtors not to the flesh, to live after the flesh. 1 John 3:2. Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know, that when he shall appear, we shall be like him; for we shall see him as he is. Ver. 3. And every man that hath this hope in him purifieth himself, even as he is pure. Psal. 130:4. But there is forgiveness with thee, that thou mayest be feared. 1 John 1:6. If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: Ver. 7. But if we walk in the light, as he is in the light, we have fellowship one with another; and the blood of Jesus Christ his Son cleanseth us from all sin.

Westminster Assembly. (1851). The Westminster Confession of Faith: Edinburgh Edition (pp. 94–98). Philadelphia: William S. Young.​

 

John stated to us, in John 20:31, that we may know and be assured that we are saved in the Son of God, Jesus, correct?

 

WLC:

Q. 81. Are all true believers at all times assured of their present being in the estate of grace, and that they shall be saved?
A. Assurance of grace and salvation not being of the essence of faith, true believers may wait long before they obtain it; and, after the enjoyment thereof, may have it weakened and intermitted, through manifold distempers, sins, temptations, and desertions; yet they are never left without such a presence and support of the Spirit of God as keeps them from sinking into utter despair.​

The persuasion (we know/attain, 1 John 5:13) that we are indeed born anew should be firmly rooted in us, yet we all are buffered about but the reed does not break. Full assurance (objective combined with subjective), when we no longer cry, How long, O Lord? Hath the Lord forgotten to be gracious?, etc., like sinless perfectionism, is not something I see us attaining until we come into our glory.

 

John seems to be saying though that if we have received Jesus as our Lord, and firmly believe that the scriptures are indeed the infallible word of the Lord unto us, that we can know with assurance that we are now redeemed and are one of ht people of God now.
Where many lack that assurance appears to be due to them not really understanding what the bbile teaches on being now born anew, what it all means to us, and by now being firmly rooted abd grounded in the scriptures themselves.
When we walk around in known sin will also cause us to have wavering doubts about being now in Jesus.

 

God does indeed want all who are saved to experience this full assurance, but due to many reasons, many do not have the confidence in them now being really redeemed and in the Family of God.

 

Assurance to one degree or another is spoken of as possible and normal, or probable for all believers.

I think AMR's quote of the WLC says more in fewer words than any other statement of the case I know of.

Consider the case of King David while steeped in the double sin of adultery and murder. He could have no sound basis for assurance during this period. Not even the Biblical promises could come to his aid before he repented. Some will say that believers never die in their apostasy but are providentially brought to an assured faith before they die. This is not true in my experience nor is it taught in the Bible.

Consider the Corinthians that died in their sin.
1 Corinthians 11:30 KJV (see in context)
For this cause many are weak and sickly among you, and many sleep.

 

The Apostle Paul in Romans 8:38-39 seems to want us to be very persuaded that as long as we fix our hope upon Jesus alone, we will know the assurance that the Holy Spirit Himself places in us as now being one of the saved of Christ.

 

Timothy, what experience have you had of those who have none, little or lost a sense of assurance? This must be a huge pastoral issue these days.

 

All who are the redeemed of the Lord can, but if they will depends on how they handle their walk with the Lord, and how they view the certainty of the scripture promises concerning assurance.
It will be nearly impossible to have full assurance if either refusing to deal with known sin issues, or when not believing and trusting what God said on this issue.

 

I thought I answered this above by showing that some Corinthians died in their sin and therefore had no assurance. Elect infants dying in infancy have no self-awareness of what we call assurance. There are many gradations of assurance from weak to strong which is usually called full assurance. But we must keep in mind that salvation does not equal assurance. If faith of all degrees = assurance, what's the big deal. Everyone is going to get it. But I can't think any Reformed confessions that teach this as an absolute.

This may seem off the subject but I just read this yesterday and found it very helpful to me. When you have time see if you too find it helpful.
I didn't take the time to add the footnotes or remove their references. Please pardon me for this.

How a Man May Know Whether He Be the Child of God, or No

Having given an overview of Perkins’s doctrine of assurance of faith, let us now examine his short treatise A Case of Conscience, The Greatest That Ever Was: How a Man May Know Whether He Be the Child of God, or No. This treatise (not counting the attached article by Jerome Zanchius)44 is six folio pages in length45 and primarily consists of a dialogue between the living church and the apostle John. The church, or the believer seeking assurance, asks questions, and John responds to the struggles of the soul with the exact words of his first epistle (Geneva Bible translation). To this Perkins added marginal notes and minor clarifications in brackets.

In addition to this short treatise, Perkins wrote two major works on conscience. The first, A Discourse of Conscience, deals with the conscience from a theoretical perspective.46 Perkins translates the biblical word for conscience as “co-knowledge” or “co-testimony.” He shows that the word itself witnesses to the divine dimension of conscience, for who can “co-know” our deepest thoughts and feelings but God and ourselves? Hence Perkins said, “Conscience is of a divine nature, and is a thing placed of God in the midst between him and man, as an arbitrator to give sentence and to pronounce either with man or against man unto God.”47 Perkins concludes that the conscience has two main duties: to give testimony and to pass judgment.48
Perkins’s largest work on conscience, The Whole Treatise of Cases of Conscience, went through thirteen English and six Continental editions to become the paradigm for numerous Puritan manuals of practical divinity.49 In this work, Perkins deals with a wide range of specific cases of conscience, covering man’s relationship to himself, to God, and to others.50 In the first section of this book, Perkins discusses what a person must do to be saved, how believers can be assured in their conscience of their salvation, and how they can be restored when they have fallen. Throughout this section, Perkins reverts to questions that relate to assurance, making it clear that he regards assurance as the greatest case of conscience.
By explicitly affirming assurance of faith as the greatest case of conscience in the title of his shorter work based on 1 John, Perkins is not falling into a kind of subjectivism that ultimately leads to unhealthy pietism, as some have affirmed. Rather, he had a more helpful goal in mind. Perkins stressed that if a person is assured of God’s favor to him in Christ, he is able to live victoriously in whatever state he finds himself. Perkins was a practical theologian; he defines theology as “the science of living blessedly for ever.” All his teaching on Christian living is based on a good conscience that rests with assurance of God’s salvation in Christ Jesus.51

In each of these works, Perkins sees a good conscience as the major purpose of John’s first epistle. In A Discourse of Conscience, Perkins devotes only one paragraph to prove this point.52 In

The Whole Treatise of Cases of Conscience, Perkins summarizes the teaching of 1 John under three propositions:
• Communion with God brings undoubted assurance (1 John 1:3–7). If we have fellowship with God, Perkins asserts, we need not worry about God’s eternal decree. In Christ we find certain salvation. We may know we are in Him by forgiveness of our sins through the blood of Christ, the work of the sanctifying Spirit within us, holiness and uprightness of heart and life, and perseverance in the knowledge of and obedience to the gospel.

• Every adopted Son of God will undoubtedly be saved (1 John 3). God’s adopted sons will truly believe in the Son of God, will strive to obey Him as Lord, and will love other Christians as their brothers and sisters, thereby giving assuring evidence of their salvation.

• Knowing the love of God provides assurance of salvation (1 John 4:9). That love, in turn, will be manifest by our love for God and our brethren.53
Perkins offered more detail on 1 John in his short treatise A Case of Conscience. When John states that he is writing so that the joy of his readers might be full (1:4), Perkins added, “i.e., might have sound consolation in your consciences.”54 Perkins repeatedly returns to the theme of conscience. He speaks of our consciences not accusing us for sin (commenting on 1 John 2:28; 3:19–21), of the “checkings and torments of conscience” (on 1 John 4:18), and of a conscience “inwardly purified” (on 1 John 5:6).55
Other bracketed comments by Perkins are like a checklist of the marks of grace by which believers may be assured in their conscience that they are adopted of God. Here are a few of those marks:

• Desiring to obey God’s commandments. On keeping God’s commandments in 1 John 2:3, Perkins notes that “to keep is not to fulfill, but to have a care and desire to do it, for God of his mercy, in his servants accepts the will for the deed.”56 Perkins is anxious not to set the bar of conversion too high, for the conscientious believer will be the first to admit that he does not keep God’s commandments as he should, though he cannot deny his desire to do so. God’s acceptance of the inward desire for the deed is most comforting for the trembling believer. At the same time it reaches what Perkins called “the inward heart motions.”

• Possessing sincerity of heart. In addressing 1 John 2:5, which speaks of the love of God being perfect, Perkins interpreted perfect as “sincere and sound perfection being opposed not to imperfection, but to hypocrisy.” When John speaks of loving in “deed and truth” (1 John 3:18), Perkins adds: “sincerely.”57 For Perkins, it is impossible to have a sound and healthy conscience without being sincere.

• Delighting in God and His grace. In commenting on 1 John 2:13, Perkins speaks three times of the delights of God’s children. He addresses fathers “delighting to tell and hear of old and ancient matters,” young men “delighting to show your valour and strength,” and children “who delight always to be under the father’s wing.”58 For Perkins, delighting in God is a key mark of grace, common to young children and old fathers in grace. Christianity that falls short of delighting in God is pharisaism.

• Fleeing the lusts of the world. Commenting on 1 John 2:16, Perkins summarizes the lust of the flesh as “the corruption of nature, which chiefly breaketh out in evil concupiscence,” the lust of the eyes as the fruit of the lust of the flesh “stirred up by outward provocations, as it is manifest in adultery or covetousness,” and the pride of life as “arrogance and ambition.” Because believers live as adopted sons and daughters, they are reckoned as the “refuse and offscouring of the world” (on 1 John 3:1).59

• Loving one another as believers. This love is the fruit of God adopting us by His grace into His family. The church responds to 1 John 3:15 by saying, “You have showed us fully that love is a work of adoption.” That adoption is possible because of God’s love for us. Perkins commented on 1 John 4:12, “That love wherewith he loveth, is thoroughly made manifest towards us by our love; as the light of the moon shining on us, argueth the light of the sun shining upon the moon, of whom (as from the fountain) the moon takes her light.”60

• Purifying of one’s self. On 1 John 3:3, Perkins made clear that believers purify themselves, but he adds that they do so as a fruit of adoption and by the grace of God. In an accompanying marginal note, Perkins says that “a desire, & an endeavor to use good means to cleanse ourselves of our corruptions and private sins is a mark of adoption.”61

Perkins reinforced these and additional marks of grace by other marginal notes, such as:
1. “Sincerity of life and religion, a note of communion with God” (1 John 1:7).
2. “Humble confession of sin to God, is a note [mark] of remission of sin” (1 John 1:9).
3. “An endeavor to keep the commandments, a sign of faith” (1 John 2:1).
4. “Love of our brother, a sign of regeneration” (1 John 2:10).
5. “God’s Spirit dwelling in the heart, a sign of perseverance” (1 John 2:20).
6. “Perseverance in the knowledge and obedience of the gospel, a sign of communion with Christ” (1 John 2:25).
7. “To love a Christian because he is a Christian or godly man, is a note of God’s child” (1 John 3:14).
8. “Compassion stirring in the heart, a note of love” (1 John 3:17).
9. “Works of mercy, signs of love” (1 John 3:18).
10. “Sincere love, a note of sincere profession” (1 John 3:19).
11. “Boldness in prayer, a sign of a pacified conscience” (1 John 3:20).
12. “The operation of Gods Spirit in sanctifying us, a sign of communion with God” (1 John 3:24).
13. “A sincere confession of the Gospel, a note of communion with Christ” (1 John 4:15).
14. “To be like God in holiness of life, is a sign of his love to us particularly” (1 John 4:17).
15. “Our love to God, a sign that he loveth us particularly” (1 John 4:19).
16. “An endeavor to obey the commandments, a sign of love of our brother” (1 John 5:2).
17. “A sign of our prayers granted us, if God do but hear them” (1 John 5:15).

Several marginal notes describe the hypocrite:
1. “Profession without practice, a note of an hypocrite” (1 John 1:6).
2. “To profess perfect sanctification in this life, a note of an hypocrite” (1 John 1:8).
3. “Faith without obedience, a note of an hypocrite” (1 John 2:4).
4. “Profession joined with hatred and malice, a note of an hypocrite” (1 John 2:9).
5. “Looseness of life or the practice of sin, a note of the child of the devil for the present time” (1 John 3:10).62

Perkins was keenly aware of the need to set all marks of grace in a trinitarian framework so that they did not result in a man-centered religion. In commenting on 1 John 4:7, Perkins wrote that believers know God “by a special knowledge, whereby they are assured that God the father of Christ is their father: Christ their Redeemer: the holy Ghost their sanctifier.”63 All assurance is christological. It is based on Christ’s merits (commenting on 1 John 2:12), received by faith in Him (on 1 John 5:4), and patterned after Him (on 1 John 3:3).64 It depends on the anointing of the Holy Spirit. Perkins viewed the ointment John refers to in 1 John 2:20, 27 as the grace of God’s Holy Spirit that we receive of Christ, which is the fulfillment of the anointings in the Old Testament.65 In sum, one may know whether he is a child of God by examining the marks of saving grace in his life as they flow out of Christ and are ratified by the anointing of the Holy Spirit.

Conclusion

Perkins’s doctrine of assurance of faith emphasized the covenant, secondary grounds of assurance, active pursuit of assurance, subjective experience, and degrees of faith more than the Reformers did.66 Perkins also stressed the role of conscience in relationship to covenantal obedience, particularly in his practical syllogism.67 In his theology, growth in grace as a sign of assurance was inseparable from a close examination of the conscience.
Perkins did not abandon the Reformers’ teaching on faith and assurance, however. Rather, his emphases rose out of pastoral concerns. Though at times Perkins emphasized salvation more than the primacy of God and His grace, he did not shift the ground of assurance from Christ, nor did he abandon sola gratia. He differed from Calvin and the Reformers in emphasis, but not in substance.
Perkins was not a voluntarist in matters of salvation.68 He asserted that the conditions of the covenant must be fulfilled, but he also said that God enables the believer to fulfill them. “He that turns to God must first of all be turned of God, and after that we are turned, then we repent,” he wrote.69 Perkins maintained that the object of saving faith is Jesus Christ, and the primary ground of assurance rests in the christological promises of a triune God as they are apprehended by faith.70

Beeke, J. R., & Jones, M. (2012). A Puritan Theology: Doctrine for Life (pp. 594–599). Grand Rapids, MI: Reformation Heritage Books.

 

Thomas Hooker said:
"Despair hath slain his thousands, and Presumption his ten thousands."
I think that is still applicable today.

 

Is not the Holy Spirit Himself bearing witness to us that we are now the children of God be a type of assurance though?