The WESTMINSTER LARGER Catechism
WLC 71.
How is justification an act of God’s free grace?A. 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 in as much 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
Proofs
1
Rom 5:8–10, 19; 21 Tim 2:5–6; Heb 10:10; Mt 20:28; Dan 9:24, 26; Isa 53:4–6, 10–12; Heb 7:22;The renowned Reformed theologian, Dr R.C. Sproul, once shocked his congregation by telling them that "our justification is entirely by works.…" Before the gasps died down, however, he explained: "…by the works of Christ alone!"
Dr Sproul is right. We are justified solely on account of what Christ has done. The benefits of our justification were entirely purchased by Christ—through His life of perfect obedience and His substitutionary death on the Cross.
But if our justification is purchased with a price, how can it be said to be "of God’s free grace"? This is the first problem that this question of our catechism seeks to explain.
The second problem is that if faith,—which is believing,—is required for our justification, then again, how can it be said to be an act of God’s free grace?
The answer to the first problem is that though our justification costs a great price (1Cor 6:20; 7:23; 1 Pet 1:18-19) to Christ our Surety (or Substitutionary-Guarantor), it costs us nothing. In fact, our Surety is provided by God Himself; and He did willingly out of His own good pleasure die to pay for the debt we owe God. Now, His payment is more than sufficient for us so that we can add nothing to it. And what’s more, God sovereignly (i.e. without our contribution) imputes or credits to us the righteousness of Christ which was obtained by a sinlessly perfect life,—in order that we may have eternal life. Surely, then it is proper to speak of justification as an act of God’s free grace.
The answer to the second problem is like unto the first, namely that faith is a gift of God (Eph 2:8). Faith is indeed believing on our part. But it is not something that we generate from our own hearts. God must change our hearts to enable us to believe. This change of heart happens at our regeneration (Eph 2:1, John 3:3). Apart from this work of grace, we can have no faith. Therefore, it is a fact that we contributed nothing at all to our justification.
Our justification is entirely an act of God’s free grace. W