Dr. Sean Lucas uses an article from Baptist pastor, John Piper, on teaching kids to pray to reason for infant baptism. He writes:
This is an interesting set of reflections from John Piper. They actually strike me as providing a pretty strong case for applying the sign of the covenant (baptism) to a child.
After all, if you are going to 1) admit that you cannot know when a child is regenerate; and 2) treat the child as though they have covenant responsibilities which arise from belonging to a Christian family (or in Piper’s language “treat them as a believer”); then 3) applying the sign of entrance into the covenant community (i.e. baptism), a sign that authenticates (or “seals”) God’s gospel promises for him and invites him to respond by faith, makes a whole lot of biblical sense.