Christian baptism has its origin in the Jewish rite of the Mikveh, or ritual bath.
This was done at various times, such as purification to attend or participate in Temple rituals, after menstruation or childbirth.
And most especially when receiving a Gentile proselyte into Judaism.
When John was baptizing in the Jordan, he was actually performing the rite of Mikveh. In effect, he was saying, “Don’t think you’re someone special because you’re descended from Abraham. You’re no better than the Gentiles who worship idols.”
In fact, immersion in the Mikveh is required even for receiving a Gentile infant of either sex that Jewish parents wish to raise in the Jewish faith.
So, you see, infant baptism is not just something that nasty ole pope feller thought up, as some Protestant controversialists claim.