A: It is the sacrifice of Jesus Christ, which originated and developed out of His voluntary obedience, or perfect love of God and neighbor. Since the One who suffered death kept the law perfectly and thus was not liable to death, I believe that such a death was complete payment not only for the evil I have done but also for the good that I should have done but failed to do. The latter is also sin and has also been erased and paid for with the obedience of Christ’s death (Phil. 2; Rom. 5; Gal. 3,4; 1 John 1)
169 Q: How would it be however, if we countered this accusation of Satan before the judgment seat of God with a kind of righteousness that derived partly from the suffering and death of Christ and partly from our good works?
A: We could not do that without great danger both to the honor of God and to our own consciences. First of all, if we should add something, however little, from our works to the righteousness that Christ has obtained for us by His suffering and death, then we could still have reason to boast in ourselves. But faith certainly and completely removes all boasting from us and ascribes it to Christ alone (Rom. 3:27, 4:2; Jer. 9:23; 1 Cor. 1:31). Therefore, we must never add even a fragment of our works, no matter how big or small it is, to the obedience or righteousness of Jesus Christ. Otherwise faith would present Christ’s righteousness before the tribunal of God as though it were not complete in itself but needed to be supplemented by us. This is what the holy apostle Paul teaches in Philippians 3:7-10.
Second, if we were to mix our own works together with the merits of Christ, we would not have a peaceful conscience. Believer’s obedience and good works are still sullied with the stains of the flesh and are imperfect; much that is sinful still clings to their good works. Thus if their works were presented before the judgment seat of God, they would of necessity be liable to the sentence that God has already pronounced in His Word, “Cursed is everyone who does not continue in all things which are written in the book of the law, to do them (Gal. 3:13). It is, therefore, easy to see that if we should depend in part on our works, even a little, our consciences could never be at peace or assured that we are justified before God and can stand in His presence. Instead they would be assured of our condemnation. As Scripture says, “As many as are of the works of the law [that is, of the opinion that they are wholly or partially justified before God by these works] are under the curse” (Gal. 3:10). Therefore, says Paul in Romans 4:16, we are freely justified through faith “so that the promise might be sure.”
The entire doctrine of justification, then, has two goals on which we should focus our attention: (1) that God alone be given the glory for justifying us (Rom. 3,4); nothing remains of which even the greatest of saints can boast, not even Abraham himself (Rom. 4:2); and (2) that our consciences be peaceful and steadfast (Rom. 4). These two goals of our justification are fundamentally altered, however, if we should add our own works, wholly or in part, to the righteousness that Christ obtained for us and freely given to us. It is only right, then, that we let the perfect righteousness that Christ obtained for us by His death suffice for us. Then we shall not be robbing Christ of His glory and shall have peace and quiet in our consciences. For it is impossible that the perfect, eternal righteousness of Christ, freely given us to be ours through faith, should lack anything before the judgment seat of God. We have absolutely nothing to worry about if we hold on to this righteousness with a genuine trust.
170 Q: You are not saying, then, that good works are useless?
A: They do not serve to make us right with God, either wholly or in part, but they do serve this purpose: after we have been freely and graciously justified through the imputation of Christ’s righteousness, we show with good works that we are thankful to God the Lord, so that God might be praised through us. That is the reason we were originally created and then redeemed, as Zachariah teaches in Luke 1:74,75: “That we, being delivered from the hand of our enemies, might serve him without fear, in holiness and righteousness that is pleasing to him all the days of our life.”
Good works are also useful because by the example of our good works we win others to Christ and keep those already won from falling away. The longer they are kept close to Christ, the more they are built up.
– Casper Olivianus, A Firm Foundation (Grand Rapids: Baker Books, 1995), 115-116