Sola fide—faith alone—is sometimes called the “material cause” of the Reformation because the substance or material of the debate between the Protestant Reformers and the Roman church concerned the instrumental means of justification. The Reformers and their opponents both understood that we must be declared righteous to endure God’s judgment and enter into eternal life. But they disagreed on the instrumental means of justification and the basis upon which the declaration is made. The Roman Catholics held that the basis of God’s declaration is the righteousness of Christ and the righteous works that we produce in cooperation with grace. They also said that the instrumental means of justification are the sacraments of baptism, which initiates people into the state of justification, and penance, which restores people to the state of justification after mortal sin. The Protestants argued that the basis for the declaration of justification is only the righteousness of Christ and that faith alone is the instrument by which this righteousness is imputed to us, or put on our record.
Romans 4:1–5; 5:12–21; 1 Corinthians 1:30; and several other passages, we have seen, together teach us that justification is based on the imputation of Christ’s righteousness through faith alone. That imputation is one side of the double exchange that happens in justification. Positively, the perfect obedience of Christ is credited to us. Negatively, sin is taken away from us. In justification, God credits us with a righteousness that is not our own but is Christ’s, and He takes our sin and puts it on Christ, who bore the divine judgment against it on the cross. “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God” (2 Cor. 5:21).
Romans 4:6–8 proclaims this removal of sin and guilt, sometimes called the non-imputation of sin because sin and guilt are not imputed to us but to Christ. Paul tells us that Psalm 32:1–2 includes David’s teaching about justification that God does not count sin against the person whom He declares righteous. It is not that justification means we are not sinners; rather, it means that the Lord no longer holds our sin against us. And this is good news indeed. Dr. R.C. Sproul writes in his book Faith Alone: “In our redemptive forgiveness God does not charge us with what we owe. He does not count our sins against us. If he did, no one (except Jesus) would ever escape his just wrath. No one but Christ would be able to stand before God’s judgment.”