Faith as the Instrument of Justification: Westminster Larger Catechism Q73 Explained

In our previous devotional on Question 72, we considered what justifying faith is: a saving grace worked in the heart of the sinner by the Spirit and Word of God, by which we receive and rest upon Christ for salvation. That naturally leads to questions like: How does this faith actually justify us in the sight of God? Is it the quality of our faith that makes us right with God, or is there something else at work? We talked about some of this before, but the Westminster Larger Catechism's next question, question 73, takes it a step further to help us understand a little better.  It asks:

"How does faith justify a sinner in the sight of God?"

Then answers with careful clarity:

"Faith justifies a sinner in the sight of God, not because of those other graces which always accompany it, nor because of the good works that are the fruits of it, nor as if the grace of faith, or any act flowing from it, were imputed to him for his justification, but only because it is an instrument by which he receives and applies Christ and his righteousness."

Faith's Role in Justification

This answer turns our attention away from faith as a virtue in itself and directs it entirely toward Christ. Faith in and of itself does not save; Christ saves. Faith simply unites us to Him. It is not the ground of justification but the means by which we lay hold of Christ and His righteousness. Scripture never presents faith as a substitute for righteousness. It is presented as a means of receiving it from the Lord. Romans 3:28 states, “For we hold that one is justified by faith apart from works of the law.” Paul doesn’t mean faith replaces works as a new kind of merit; instead, he means that faith connects us to Christ, who truly justifies. Likewise, Galatians 2:16 explains that we are justified “through faith in Christ and not by works of the law, because by works of the law no one will be justified.” Thus, justification is not dependent upon the strength of our belief but upon the sufficiency of the One in whom we believe.

Faith Is Not the Basis, but the Instrument

The catechism is careful to clarify that faith does not justify because of the presence of other graces, such as repentance, love, or humility, nor because faith produces good works that might commend us to God. Even the act of believing itself is not credited as righteousness. These clarifications protect us from turning faith into a work. If faith justified us because it was sincere or strong, then the believer would never escape inward anxiety that asks questions like: Have I believed enough? Did I believe properly? Was my faith sincere yesterday? These are the kind of questions that Martin Luther struggled with and led him to say, "I did not love, yes, I hated the righteous God who punishes sinners, and secretly, if not blasphemously…I was angry with God" (Preface to the Complete Edition of Luther's Latin Writings). What Luther lacked was the understanding that faith does not work for righteousness; it receives the righteousness of Christ.

The gospel directs us away from the condition of our hearts and toward the condition of our Savior. Faith justifies because it receives Christ, not because it presents something valuable to God. As Paul wrote in Romans 4:5, "To the one who does not work but believes in him who justifies the ungodly, his faith is counted as righteousness." What is counted is not faith's merit, but Christ's righteousness, applied to the believing sinner.

Understanding Faith Through Analogy

To grasp this clearly, it may be helpful to think of faith as an extension cord. An extension cord does not create electricity; it merely connects what needs power to the source that already possesses it. The light in the room does not depend on the cord itself, but on the power that flows through it. In the same way, faith does not generate salvation, nor does it contribute anything to it. Faith contains no saving power within itself. It simply connects the sinner to Christ, in whom all saving power resides. Faith is valuable only because of its object. The strength of salvation lies not in the strength of our believing but in the sufficiency of Christ, to whom faith is united. This is why Scripture never calls us to look at our faith, but always to look to Christ.

Hope for Weak or Struggling Faith

This truth provides deep comfort to weary believers. There are seasons when our faith feels frail and uncertain. Some believers fear they cannot be justified because they do not feel strong in faith. Yet Scripture shows that even imperfect faith, as long as it rests on a perfect Savior, receives the whole Christ. The one who says, "Lord, I believe—help my unbelief," has already come to the right place. Weak faith united to a strong Christ receives all the benefits of salvation. Our assurance does not rest on our ability to hold Christ, but on His promise to hold us. In John 10:28, Jesus declares, "I give them eternal life, and they will never perish, and no one will snatch them out of my hand."

Living a Life Shaped by Justifying Faith

Understanding justification by faith alone transforms the daily life of the believer. It frees us from living as spiritual performers and teaches us instead to live as grateful recipients of grace. We no longer obey in order to earn acceptance, for we are already accepted. We do not live under the shadow of shame but under the banner of Christ's righteousness. This truth turns duty into delight and obedience into worship. When we fail, we do not run away from God; we run to Him, knowing that our failures have not separated us from him. The righteousness that justifies cannot be improved, increased, or threatened because it is the righteousness of Christ Himself.

This is not simply a doctrine to understand but a truth to live by. Faith is more than an event in the past; it becomes a daily posture of the soul. Each morning, it looks away from self and toward Christ. Each trial drives it to rest in His sufficiency. Each sin leads it to trust once more in His grace. In this way, the believer learns to breathe spiritually: not by exalting self, but by continually receiving Christ. Faith justifies precisely because it abandons hope in self and lays hold of the Savior. And where faith rests in Him, the verdict stands forever: forgiven, righteous, accepted, and secure.

Soli Deo Gloria.