“The next day he saw Jesus coming toward him, and said, ‘Behold, the Lamb of God, who takes away the sin of the world! This is he of whom I said, “After me comes a man who ranks before me, because he was before me.” I myself did not know him, but for this purpose I came baptizing with water, that he might be revealed to Israel.” (John 1: 29-31 ESV )
Purpose