Expositor's Bible Commentary Commentary John 1:31

"And I knew him not; but that he should be made manifest to Israel, for this cause came I baptizing in water." — John 1:31 (ASV)

The identity of the Messiah was unknown to John the Baptist. This does not mean that John did not know Jesus personally, for, after all, they were relatives . John’s ministry was twofold: he was to lead his hearers to repentance (Mark 1:4) and to reveal the Messiah to Israel. Somehow John understood that the revelation of Messiah would take place in conjunction with his baptizing ministry; therefore, he remained faithful to his calling. However, even after Messiah had been revealed to Israel at the baptism of Jesus, John continued the other aspect of his ministry.