Bavinck on so called “free grace”

Related to these two are those one-sided conceptions of the order of salvation known as antinomianism and neonomianism. The former reduces the application of salvation to and virtually equates it with its acquisition, thereby eschewing all works; the latter reinstitutes the law. In antinomianism Christ has accomplished everything, removing not only the guilt of our sin but also its pollution. Sanctification is already ours, there is nothing left for humans to do. Any talk of “doing” is legalism; all we have to “do” is believe, i.e., come to the insight that we are already perfect in Christ or set aside the illusion that God is angry with us. Here sin is an illusion and leads to anarchy. In ancient times such sentiments were propagated by gnostic and Manicheans, in the Middle Ages by numerous libertine sects, and during and after the Reformation they revived among the Anabaptists, in the sect of the Libertines, in the independentistic disturbances in England around the middle of the seventeenth century.
Bavinck, Reformed Dogmatic, Abridged One Volume, pp. 483-484