What’s the difference between legalism and antinomianism? The latter is the denial of the abiding validity of God’s moral law for the life of the believer. The church has been afflicted with antinomianism throughout its history. All the Gnostics of the 2nd century drew an absolute line between Abraham, Moses, David et al and the New Covenant. They taught that the “Old Testament” god was a demiurge (a sort of semi-deity). The law, because it was articulated under Moses, had no bearing in the New Covenant. They had a pagan doctrine of creation. They did not realize that the law was not first given under Moses, that it was first given in creation by God. They didn’t see the goodness of the law because they didn’t see the goodness of creation or the Mosaic law as a re-articulation of the law given in creation. There were antinomians in the middle ages, e.g., the Cathars/Albigensians, and there were antinomians in the 16th century. The latter were thoroughly repudiated by Luther and the rest of the magisterial Reformers.
Legalism in justification is the doctrine that we are capable of keeping the law in order to be justified and that we must do so. Inasmuch as the medieval church adopted the notion that, in a state of grace, we have the power freely to cooperate with grace, she effectively taught a legalistic doctrine of justification through grace and works. The Anabaptists rejected the Protestant doctrine of free acceptance with God through faith alone. Legalism persisted into the 17th century. Richard Baxter taught justification through sanctification about the same time his opposites, the English antinomians, were denying the validity of the moral law for the believer (the tertius usus legis, the third use of the law). Today we are beset by both errors. This episode of the Heidelcast opens the mail and tackles this issue.