Clarity on the role of faith in our justification is essential if we are to understand the biblical witness regarding our right standing before God the Father Almighty. Like every other biblical doctrine, justification is rightly comprehended only when we take all of Scripture into account. If, for example, we were to take a passage like Galatians 2:15–16 in isolation from the rest of the Bible, we might be tempted to believe that justification is a reward for our faith. In other words, we might think that faith merits our right standing before the Lord.
Yet when we say that justification is by faith alone, we are not saying that God considers our faith meritorious and, on that basis, justifies us. If we see justification as a reward for our faith, we rely on the merit of something we do, and nothing sinners do — even the act of faith — is good enough before the bar of the Lord’s justice. Of course, faith is God’s gift. His Spirit must change our hearts of stone into hearts of flesh before we have the moral ability to believe the gospel (Ezek. 11:17–20; Eph. 2:8–10). All whom God regenerates in this manner will come to faith. However, though the Lord enables us to have faith, the faith we exercise is still our faith. It still comes from flawed hearts, even if these hearts beat with love for God on account of His work. At times, we have to cry out for Him to help our unbelief (Mark 9:24). If justification were a reward for our faith, no one could be justified, for we must turn from unbelief to belief in God’s promises every day of our lives.
We say that we are righteous through faith alone because faith is the only means by which we can lay hold of Christ’s righteousness (The Heidelberg Catechism, Q&A 61). The Apostle Paul tells us in today’s passage that Christ is our righteousness. His work is the material cause of our justification, the stuff out of which the Father formulates His declaration that we are just in His sight. Faith, on the other hand, is the instrumental cause of our justification, the instrument by which we lay hold of this righteousness and enjoy its imputation to our accounts. Our faith need not be absolutely perfect to lay hold of this righteousness, for, thanks be to God, Jesus atoned also for the sin of doubt. Those whose faith is real, albeit imperfect, demonstrate such faith in a life of repentance (1 John 1:8–9; 2:1).