Wherein do justification and sanctification differ?
Although sanctification be inseparably joined with justification,1 yet they differ, in that God in justification imputeth the righteousness of Christ;2 in sanctification his Spirit infuseth grace, and enableth to the exercise thereof;3 in the former, sin is pardoned;4 in the other, it is subdued:5 the one doth equally free all believers from the revenging wrath of God, and that perfectly in this life, that they never fall into condemnation;6 the other is neither equal in all,7 nor in this life perfect in any,8 but growing up to perfection.9
Scripture proofs
The Westminster Assembly's proof texts (KJV). The bracketed numbers in the answer above mark the clause each set of references supports; expand a row to read the verses.
1 1 Cor. 1:30; 1 Cor. 6:11
But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:
And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
2 Rom. 4:6, 8
Rom. 4:6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,
Rom. 4:8 Blessed is the man to whom the Lord will not impute sin.
3 Ezek. 36:27
And I will put my spirit within you, and cause you to walk in my statutes, and ye shall keep my judgments, and do them.
4 Rom. 3:24–25
Rom. 3:24 Being justified freely by his grace through the redemption that is in Christ Jesus:
Rom. 3:25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
5 Rom. 6:6, 14
Rom. 6:6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin.
Rom. 6:14 For sin shall not have dominion over you: for ye are not under the law, but under grace.
6 Rom. 8:33–34
Rom. 8:33 Who shall lay any thing to the charge of God’s elect? It is God that justifieth.
Rom. 8:34 Who is he that condemneth? It is Christ that died, yea rather, that is risen again, who is even at the right hand of God, who also maketh intercession for us.
7 1 John 2:12–14; Heb. 5:12–14
1 John 2:12 I write unto you, little children, because your sins are forgiven you for his name’s sake.
1 John 2:13 I write unto you, fathers, because ye have known him that is from the beginning. I write unto you, young men, because ye have overcome the wicked one. I write unto you, little children, because ye have known the Father.
1 John 2:14 I have written unto you, fathers, because ye have known him that is from the beginning. I have written unto you, young men, because ye are strong, and the word of God abideth in you, and ye have overcome the wicked one.
Heb. 5:12 For when for the time ye ought to be teachers, ye have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat.
Heb. 5:13 For every one that useth milk is unskilful in the word of righteousness: for he is a babe.
Heb. 5:14 But strong meat belongeth to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil.
8 1 John 1:8, 10
1 John 1:8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
1 John 1:10 If we say that we have not sinned, we make him a liar, and his word is not in us.
9 2 Cor. 7:1; Phil. 3:12–14
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.
Phil. 3:12 Not as though I had already attained, either were already perfect: but I follow after, if that I may apprehend that for which also I am apprehended of Christ Jesus.
Phil. 3:13 Brethren, I count not myself to have apprehended: but this one thing I do, forgetting those things which are behind, and reaching forth unto those things which are before,
Phil. 3:14 I press toward the mark for the prize of the high calling of God in Christ Jesus.
This doctrine across the Standards
Where the Confession and the Westminster Shorter Catechism treat the same matter, so the question can be studied alongside its parallel statements.
In the Westminster Confession
XIII.1 They who are effectually called and regenerated, having a new heart and a new spirit created in them, …
They who are effectually called and regenerated, having a new heart and a new spirit created in them, are further sanctified, really and personally, through the virtue of Christ's death and resurrection, by his Word and Spirit dwelling in them; the dominion of the whole body of sin is destroyed, and the several lusts thereof are more and more weakened and mortified, and they more and more quickened and strengthened, in all saving graces, to the practice of true holiness, without which no man shall see the Lord.
→ XIII.1 · Of SanctificationXIII.2 This sanctification is throughout in the whole man, yet imperfect in this life; there abideth still some remnants …
This sanctification is throughout in the whole man, yet imperfect in this life; there abideth still some remnants of corruption in every part, whence ariseth a continual and irreconcilable war, the flesh lusting against the spirit, and the spirit against the flesh.
→ XIII.2 · Of SanctificationXIII.3 In which war, although the remaining corruption for a time may much prevail, yet, through the continual supply …
In which war, although the remaining corruption for a time may much prevail, yet, through the continual supply of strength from the sanctifying Spirit of Christ, the regenerate part doth overcome; and so the saints grow in grace, perfecting holiness in the fear of God.
→ XIII.3 · Of SanctificationIn the Westminster Shorter Catechism
Q.35 What is sanctification?
Sanctification is the work of God's free grace, whereby we are renewed in the whole man after the image of God, and are enabled more and more to die unto sin, and live unto righteousness.
→ Open Q.35Q.36 What are the benefits which in this life do accompany or flow from justification, adoption, and sanctification?
The benefits which in this life do accompany or flow from justification, adoption, and sanctification, are, assurance of God's love, peace of conscience, joy in the Holy Ghost, increase of grace, and perseverance therein to the end.
→ Open Q.36