What Is Justifying Faith? | Receiving and Resting in Christ Alone (Westminster Larger Catechism Q72 Explained)

Faith is one of the most familiar words in Christianity, yet one of the most misunderstood. Many people think of faith as optimism, determination, or hoping things will somehow work out. But justifying faith, the faith that actually saves, is far deeper than that. So what is it?

The Westminster Larger Catechism asks this very question in its 72^nd question:

“What is justifying faith?”

The answer is enlightening:

“Justifying faith is a saving grace, worked in the heart of a sinner by the Spirit and Word of God, by which the sinner, being convinced of his sin and misery and of the inability of himself and all other creatures to save him out of his lost condition, not only assents to the truth of the promise of the Gospel, but also receives and rests on Christ and his righteousness, held forth in the Gospel, for the pardon of his sin and for the acceptance and accounting of his self as righteous in the sight of God, for his salvation.”

The Spirit’s Work: Awakening Faith in the Heart

Faith is not something we create within ourselves. The Catechism calls it a “saving grace, worked in the heart by the Spirit and Word of God.” Faith comes when the Spirit brings a sinner face-to-face with the truth: that he is guilty, helpless, and unable to save himself.

Romans 10:17 says, “Faith comes from hearing, and hearing through the word of Christ.” The Spirit and the Word work together. The Word reveals the Gospel promise; the Spirit opens the heart to receive it. 1 Corinthians 2:14 reiterates the necessity of the Spirit’s work when it says, “The natural man does not accept the things of the Spirit of God, for they are folly to him.” What begins as conviction of sin becomes a cry for mercy, and that cry finds its answer in Jesus Christ.

The Threefold Nature of Saving Faith

The Reformed tradition has long described true, justifying faith as having three inseparable parts: knowledge, assent, and trust. These aren’t three different kinds of faith, but three essential aspects of one living faith that unites us to Christ.

1. Knowledge (Notitia) — Knowing the Truth

Saving faith begins with knowledge. You can’t believe what you don’t know. The Gospel must be understood before it can be trusted. Faith is not blind; it’s rooted in the revealed truth of Scripture—who Christ is, what He’s done, and what He promises.

This is why the Spirit works through the Word. The believer learns that Jesus is the eternal Son of God who lived a sinless life, died for sinners, and rose from the grave. Knowledge gives content to faith.

2. Assent (Assensus) — Agreeing with the Truth

But knowledge alone isn’t enough. Many people know Gospel facts without being changed by them. Saving faith also involves assent—a heartfelt agreement that what God says is true.

This is what the Catechism means when it says that faith “assents to the truth of the promise of the Gospel.” The believer doesn’t just know about Christ; he is convinced that God’s promise of salvation through Christ is reliable, sure, and good. Yet even assent, by itself, stops short. The demons believe the truth about Christ (James 2:19), but they don’t trust Him. That brings us to the final and most personal aspect of faith.

3. Trust (Fiducia) — Resting in Christ

True faith doesn’t only know and agree; it rests. The Catechism says the believer “receives and rests on Christ and His righteousness.” That’s the language of trust; of relying entirely upon Jesus as Savior and Lord.

This is faith at its fullest expression: the soul leaning all its weight on the cross of Christ. It’s the confidence that His righteousness is enough, His sacrifice sufficient, His promise unshakable. As Jesus said, “Come to me, all who labor and are heavy laden, and I will give you rest” (Matthew 11:28). That resting is not laziness but surrender; ceasing to depend on self and relying entirely on Christ.

The Object of Faith: Christ and His Righteousness

Faith’s power lies not in its strength but in its object. We are not saved because of the greatness of our faith but because of the greatness of Christ. Philippians 3:9 beautifully summarizes this: “And be found in him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ—the righteousness from God that depends on faith.”

Faith does not save in and of itself; it connects us to the One who does. Christ’s righteousness is credited to the believer’s account, while our sin was imputed to Him at the cross. That’s justification; our pardon and acceptance before God based solely on Christ’s obedience and sacrifice.

Faith Is a Gift: Grace from Start to Finish

The Catechism calls justifying faith a “saving grace.” That means even faith itself is a gift of God. Ephesians 2:8-9 reminds us, “For by grace you have been saved through faith. And this is not your own doing; it is the gift of God.”

We don’t produce faith by our willpower. God grants it through the regenerating work of the Holy Spirit. This truth humbles us and fills us with gratitude: every step of salvation, from conviction to faith to justification, is grace upon grace.

Living by Faith: The Daily Rhythm of Rest

Justifying faith isn’t something we leave behind after conversion; it becomes the rhythm of the Christian life. We continue to “receive and rest” on Christ each day. Galatians 2:20 says, “The life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me.” Faith is how we walk, not just how we begin. When we stumble, we rest in His mercy. When we doubt, we rest in His promises. When we fear, we rest in His strength.

Faith is not a one-time act but a lifelong dependence on the same Christ who saved us.

A Word for the Weary

If your faith feels small, take heart. It is not the strength of your faith that saves you, but the strength of your Savior. Even a trembling hand that reaches for Christ receives all of Him.

Faith’s essence is not perfection but direction; it looks away from self and toward Jesus. The Gospel calls you to stop striving and rest. To know, to assent, and to trust. That is justifying faith; God’s gift that brings sinners into the peace and righteousness of Christ.

Soli Deo Gloria