Semper Reformanda on John’s baptism:
“So, when John was calling people, he was calling Jews. What would a Levite have to do with Gentiles and Samaritans? This was for the people of God. These peoples included the federal heads of the family. The federal headship understood the gravity of what their job was. They always functioned as a family unit. It was never individual; no one was independent of the federal headship. Federal heads had already placed the sign on their children prior to this event. There is no way that a faithful Jew would have thought for a moment that this washing was a replacement to the covenantal command to circumcise; it was in addition to.
The point is, John was actually a paedobaptist. Paedobaptists function along the same lines as the Old testament saint in regards to the sign. In the Old, there was circumcision, in the new, there is water baptism.”