Where did baptism come from?

Question from moody radio listener on openline on April 8, 2015: I want to know where baptism came from? It's not mentioned in the old testament as far as I know and then new testament starts with John the Baptist baptizing.  So where did baptism come from? Answer from Dr Michael Rydelnik: It's really simple. If you go to Leviticus, you see all these washings, like the priestly washings and purity washings, that's the source of baptism. By the time you come to the intertestamental period,  the rabbis have established all kinds of ritual baths that people participated in and there are a variety of reasons, there are some for converts to Judaism, the ritual purity for women after their monthly cycle, men with all sorts of symbol cleansing from sin, there are all kinds like the high priest would undergo ritual washing to enter into his office, all sorts of ritual washings that are rooted in the book of Leviticus, Numbers and all sorts of places like that. That's where it comes from and so when John the Baptist shows up and he's baptizing, no one says hmm what's he doing? It fully fits the culture of the day. They understood exactly where it is coming from. It develops from the pentateuch, goes into intertestamental period with all the  rabbinic washings and then we get new testamental washings that are just part of the culture on that day and time and then John the Baptist and then the Lord Jesus gives it its own special believing significance. Hope that helps.