I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and [with] fire:
Note 4 at Mt 3:11: John the Baptist introduced baptism as we know it in the church today. Under the Old Covenant there were many "washings" (Heb 9:10) that may have symbolized baptism, but it had not been done unto repentance (Mr 1:4), as John administered it. However, the Jews didn't question baptism and even expected it to be a practice of the Christ and of the messenger whom God would send before Him (Joh 1:25). John baptized for two reasons. The first was for the remission of sins (Mr 1:4 and Lu 3:3). The Greek word "EIS" was translated "for" in those verses and was also translated as "to the intent that" and "(so) that" (Strong's Concordance). The second reason was to make Jesus "manifest" (or known) to the nation of Israel (Joh 1:31).