One can say, therefore, that every criticism of infant baptism runs the danger of falling back on the position of the Anabaptists, who always started from the contrast between nature and grace. They could not believe that “the natural” could have a place in the Covenant, because they thought that this threatened “the spiritual” of the Covenant. The Reformers, however, always maintained that the contrast was not between nature and grace, but between flesh and spirit, sin and grace, and that for that reason the richness of baptism could not be threatened by normal life, unless it be through superficiality. The position of the Reformers is inviolable here. It rests immediately upon Scripture. Against those who asked for a direct scriptural proof in which infant baptism was divinely commanded, the Reformers courageously pointed at the injustice of this question. In response, they asked their critics precisely where the Bible says that this fundamental Covenant relation is broken in the New Covenant.

– G.K. Berkouwer, The Sacraments.