I was asked this yesterday at Presbytery in casual conversation and realized I have no idea. I know the Nicene Creed (“one baptism for the remission of sins”) is appealing to Ephesians 4 with Acts 2 and Peter’s call for repentance in the first sermon of the Church. But I have never researched if there is any contemporary evidence for some agreed upon theory about the hows and whys and whens of baptism and the remission of sins. I simply have no information about what the average Christian at the time of Nicea believed about baptism and forgiveness and all things related.

I do know that during the Reformation there was a debate about the forgiveness of sins and baptism between the Protestants and the Roman Catholics. Since it is commonly believed the Lutherans and the Reformed disagreed with each other about this issue, I’ll limit my remarks to what was held as being the difference with the Roman Catholics on the part of the Reformed.

John Calvin explained it this way:

I know it is a common belief that forgiveness, which at our first regeneration we receive by baptism alone, is after baptism procured by means of penitence and the keys. But those who entertain this fiction err from not considering that the power of the keys, of which they speak, so depends on baptism, that it ought not on any account to be separated from it. The sinner receives forgiveness by the ministry of the Church; in other words, not without the preaching of the gospel. And of what nature is this preaching? That we are washed from our sins by the blood of Christ. And what is the sign and evidence of that washing if it be not baptism? We see, then, that forgiveness has reference to baptism. This error had its origin in the fictitious sacrament of penance, on which I have already touched. What remains will be said at the proper place. There is no wonder if men who, from the grossness of their minds, are excessively attached to external things, have here also betrayed the defect, not contented with the pure institution of God, they have introduced new helps devised by themselves, as if baptism were not itself a sacrament of penance. But if repentance is recommended during the whole of life, the power of baptism ought to have the same extent. Wherefore, there can be no doubt that all the godly may, during the whole course of their lives, whenever they are vexed by a consciousness of their sins, recall the remembrance of their baptism, that they may thereby assure themselves of that sole and perpetual ablution which we have in the blood of Christ (John Calvin, Institutes, IV, 15, 4; emphasis added).

The Council of Trent actively assaulted the Reformed on this very point. The condemning sentence reads:

If anyone says that by the sole remembrance and the faith of the baptism received, all sins committed after baptism are either remitted or made venial, let him be anathema.

Of course, many times in Trent one finds only a charicature of Reformed Doctrine being condemned. But in this case, the Reformed identified this cursing as a cursing of true doctrine. This basic position was still considered orthodox and Reformed as late as the time of Francis Turretin:

Does baptism… take away past and present sins only and leave future sins to repentances? Or does it extend itself to sins committed not only before but also after baptism? The former we deny; the latter we affirm against the Romanists.… II… [T]he Romansists teach… “The virtue of baptism does not reach to future sins, but the sacrament of penitence is necessary for their expiation.” Thus, the Council of Trent expresses it: “If anyone shall say that all the sins which are committed after baptism are either dismissed or made venial by the recollection of faith of the received baptism alone, let him be anathema (session 7, Canon 10, Schroeder, p. 54)….

XII. …However, we maintain that by baptism is sealed to us the remission not only of past and present, but also of future sins; still so that penitence (not a sacramental work and what they invent, but that which is commanded in the gospel) and especially saving faith is not excluded, but is coordinated with baptism as a divinely constituted means of our salvation (Francis Turretin, Institutes of Elenctic Theology, vol. 3).

So the difference between the Reformed and the Romanist seems to be that the Roman Catholics limited baptism’s efficacy more than the Reformed thought was right. Also, the Reformed saw no conflict between faith and baptism whereas the Romanists seemed to divide these things so that faith became understood as insufficient for salvation.