How is justification an act of God's free grace?
Although Christ, by his obedience and death, did make a proper, real, and full satisfaction to God's justice in the behalf of them that are justified;1 yet inasmuch as God accepteth the satisfaction from a surety, which he might have demanded of them, and did provide this surety, his own only Son,2 imputing his righteousness to them,3 and requiring nothing of them for their justification but faith,4 which also is his gift,5 their justification is to them of free grace.6
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 Rom. 5:8–10, 19
Rom. 5:8 But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.
Rom. 5:9 Much more then, being now justified by his blood, we shall be saved from wrath through him.
Rom. 5:10 For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life.
Rom. 5:19 For as by one man’s disobedience many were made sinners, so by the obedience of one shall many be made righteous.
2 2 Tim. 2:5–6; Heb. 7:22; Heb. 10:10; Matt. 20:28; Dan. 9:24, 26; Isa. 53:4–6, 10–12; Rom. 8:32; 1 Pet. 1:18–19
2 Tim. 2:5 And if a man also strive for masteries, yet is he not crowned, except he strive lawfully.
2 Tim. 2:6 The husbandman that laboureth must be first partaker of the fruits.
By so much was Jesus made a surety of a better testament.
By the which will we are sanctified through the offering of the body of Jesus Christ once for all.
Even as the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many.
Dan. 9:24 Seventy weeks are determined upon thy people and upon thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy.
Dan. 9:26 And after threescore and two weeks shall Messiah be cut off, but not for himself: and the people of the prince that shall come shall destroy the city and the sanctuary; and the end thereof shall be with a flood, and unto the end of the war desolations are determined.
Isa. 53:4 Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted.
Isa. 53:5 But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.
Isa. 53:6 All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all.
Isa. 53:10 Yet it pleased the LORD to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand.
Isa. 53:11 He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities.
Isa. 53:12 Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he hath poured out his soul unto death: and he was numbered with the transgressors; and he bare the sin of many, and made intercession for the transgressors.
He that spared not his own Son, but delivered him up for us all, how shall he not with him also freely give us all things?
1 Pet. 1:18 Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers;
1 Pet. 1:19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
3 2 Cor. 5:21
For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
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 Eph. 2:8
For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
6 Eph. 1:7
In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace;
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
XI.1 Those whom God effectually calleth he also freely justifieth; not by infusing righteousness into them, but by pardoning …
Those whom God effectually calleth he also freely justifieth; not by infusing righteousness into them, but by pardoning their sins, and by accounting and accepting their persons as righteous: not for anything wrought in them, or done by them, but for Christ's sake alone; nor by imputing faith itself, the act of believing, or any other evangelical obedience to them, as their righteousness; but by imputing the obedience and satisfaction of Christ unto them, they receiving and resting on him and his righteousness by faith; which faith they have not of themselves, it is the gift of God.
→ XI.1 · Of JustificationXI.2 Faith, thus receiving and resting on Christ and his righteousness, is the alone instrument of justification; yet is …
Faith, thus receiving and resting on Christ and his righteousness, is the alone instrument of justification; yet is it not alone in the person justified, but is ever accompanied with all other saving graces, and is no dead faith, but worketh by love.
→ XI.2 · Of JustificationXI.3 Christ, by his obedience and death, did fully discharge the debt of all those that are thus justified, …
Christ, by his obedience and death, did fully discharge the debt of all those that are thus justified, and did make a proper, real, and full satisfaction to his Father's justice in their behalf. Yet inasmuch as he was given by the Father for them, and his obedience and satisfaction accepted in their stead, and both freely, not for anything in them, their justification is only of free grace; that both the exact justice and rich grace of God might be glorified in the justification of sinners.
→ XI.3 · Of JustificationXI.4 God did, from all eternity, decree to justify all the elect, and Christ did, in the fulness of …
God did, from all eternity, decree to justify all the elect, and Christ did, in the fulness of time, die for their sins, and rise again for their justification: nevertheless, they are not justified until the Holy Spirit doth, in due time, actually apply Christ unto them.
→ XI.4 · Of JustificationXI.5 God doth continue to forgive the sins of those that are justified; and although they can never fall …
God doth continue to forgive the sins of those that are justified; and although they can never fall from the state of justification, yet they may by their sins fall under God's fatherly displeasure, and not have the light of his countenance restored unto them, until they humble themselves, confess their sins, beg pardon, and renew their faith and repentance.
→ XI.5 · Of JustificationXI.6 The justification of believers under the Old Testament was, in all these respects, one and the same with …
The justification of believers under the Old Testament was, in all these respects, one and the same with the justification of believers under the New Testament.
→ XI.6 · Of JustificationXIV.2 By this faith a Christian believeth to be true whatsoever is revealed in the Word, for the authority …
By this faith a Christian believeth to be true whatsoever is revealed in the Word, for the authority of God himself speaking therein; and acteth differently upon that which each particular passage thereof containeth; yielding obedience to the commands, trembling at the threatenings, and embracing the promises of God for this life and that which is to come. But the principal acts of saving faith are accepting, receiving, and resting upon Christ alone for justification, sanctification, and eternal life, by virtue of the covenant of grace.
→ XIV.2 · Of Saving FaithIn the Westminster Shorter Catechism
Q.33 What is justification?
Justification is an act of God's free grace, wherein he pardoneth all our sins, and accepteth us as righteous in his sight, only for the righteousness of Christ imputed to us, and received by faith alone.
→ Open Q.33