Preaching on Peter’s explanation of why “we must obey God rather than human beings,” the Swiss reformer Rudolf Gwalther (1519–1586) recognizes the gospel tersely stated.

Here Peter teaches that Christ pays for us a debt that we cannot pay and bestows on us a righteousness that we cannot achieve.

The Benefits of Christ Are Repentance and Forgiveness

Although a person is converted to God, our salvation is still not perfect and full. When we are sinners, we still have need of forgiveness and satisfaction, since nothing else will satisfy God’s justice. But as we have said even now that we could not convert to God unless we were regenerated by Christ, much less can we satisfy for our sins. And Christ teaches us that our sins are such a debt that we are not able to pay.

Therefore, just as in the first part, Christ supported our infirmity, so in this also he helps us. By the merit of his death he both purges the debt of our sin and makes us just in the sight of God, while he bestows his righteousness on us who believe in him. Therefore, he became sin for us, that we by his means should be that righteousness which is acceptable before God. Both these things without which no one can be saved come as benefits of Christ alone. . . .

This is the reason that [Peter], comprehending the sum of the gospel in few words, teaches that repentance and forgiveness of sins must be preached in his name.

Acts, eds. Esther Chung-Kim and Todd R. Hains, Reformation Commentary on Scripture, NT Vol. VI, p. 68.