Every year, one of my students presents on a section of Calvin’s Antidote to the Council of Trent, and I’m impressed again with how Calvin responds to Trent’s claims about baptism. The first decree of the fifth session includes this statement: “Whosoever asserts that this sin of Adam, which is one by origin, and which transfused, by propagation, not by imitation, is proper to each individual, is taken away either by the power of human nature or by some other remedy than the merit of one Mediator, our Lord Jesus Christ, who reconciled God to us in his own blood, being made unto us righteousness, and sanctification, and redemption; or denies that this merit of Christ Jesus is applied to infants as well as adults by the Sacrament of Baptism duly conferred after the form of the Church, let him be anathema.”
Calvin responds: “We assert that the whole guilt of sin is taken away in baptism, so that the remains of sin still existing are not imputed. That this may be more clear, let my readers call to mind that there is a twofold grace in baptism, for therein both remission of sins and regeneration are offered to us. We teach that full remission is made, but that regeneration is only begun and goes on making progress during the whole of life. Accordingly, sin truly remains in us, and is not instantly in one day extinguished by baptism, but as the guilt is effaced it is null in regard to imputation.”
Calvin does not say, “Baptism doesn’t remit sins.” He agrees that it does; he is completely Nicene. He also says that “regeneration” or renewal is initiated by baptism, though it continues throughout the life of the baptized. His argument with the Tridentine decree is not about the efficacy of baptism but with the question of whether concupiscence counts as sin (he says it does).