Why did John Baptize?

Why did John  baptize? The question could be perceived to be rather mundane because most Christians assume baptism  as a given rite of passage. But when the New Testament is viewed as a continuation of the Old Testament,  it becomes vital to track ordinances either in continuing Old Testament traditions or New Testament commandments. Interestingly, the Old Testament is absolutely silent on baptism. To be sure, there are pictures of baptism (the deliverance of Noah from/through the flood, the cleansing of Naaman) and anachronistic allusions to cleansing of God's people with water (Ezekiel 16:9), but no references to an establishment of covenantal rite through baptism. How then was it possible for John the baptist to employ a new ordinance and for the Lord Jesus to use it in commandment? Where can be find the origins of this new action?

(It would be an interesting study to explore inter-testamental traditions involving water but would have little bearing on the Church's use and understanding of baptism unless its seen in scripture.)

The answer seems be hidden in plain sight in the first chapter of John. John here is engaging the messengers of the pharisees  The pharisees here are intrigued by John's understanding of his own identity (1:19, 21, 22). In particular they are interested to know if John thinks of himself as the Messiah, Elijah or the (interestingly not 'a') prophet. John responds that he is nether of them. Their attention immediately drifts not to his unique lifestyle or to his preaching but to his use of baptism. They seem to be demonstrating a general awareness of baptism because their question is pointed to his authority in doing it and not what he is doing.

In the ensuing verses, lies insight into the origins of baptism. 

v31: I myself did not know him, but for this purpose I came baptizing with water, that he might be revealed to Israel.

John is clear that the reason he baptizes is so that the messiah could be revealed to Israel. He qualifies the statement by saying that the identity of the messiah was not revealed to him (before he started baptizing). He reiterates this in verse 33 both to create a logical connection to verse 31 and for greater emphasis.

v33: I myself did not know him, but he who sent me to baptize with water said to me, ‘He on whom you see the Spirit descend and remain, this is he who baptizes with the Holy Spirit.’

This verse sheds significant light on the origins of baptism. For one, its clear that there was someone who sent him to baptize with water. In other words, this was not his invention. It was a commandment, a charge. The anonymity of the sender coupled with the lack of the objection from the hearer points to the sender being sourced in God. Secondly, John expounds verse 31 in verse 33 by saying that the means of the Messiah's revelation was the Spirit descending on Him (evidently at the time of baptism). And the glorious Lord Jesus was revealed to be the messiah by this very means!

These words make it clear that the origins of baptism, according to the Bible, are in God's charge to John. Its quite possible that John may not have understood the covenantal signs in and through baptism and its imagery to the death, burial and resurrection of the Messiah but God used John's precursory baptismal tradition to prepare the path for the commandment of the Lord Jesus (Matthew 28:19) and the use of baptism in the Church.