When John the Baptist came into the wilderness of Judea with his message and baptism of repentance, he was not foisting upon the people a new and strange ceremony of which they had never heard. On the contrary, divers washings, many different kinds of Levitical baptisms, had been known to the Jews since the time of Moses. The rite originated in the ceremonial lustration of the unclean, Gen. 35, 2; Ex. 19, 10; Num. 19, 7; Judith 12, 7, and was soon extended to embrace every form of Levitical purifying that was done with water, Heb. 9, 10.
One of the earliest forms of religious ablutions was the baptism of the priests at their consecration, Ex.29, 1—9; 40, 12. There is an allusion to this washing of the priests in Heb. 10, 22. Any defilement of the body contracted by the priests after their installation, in the daily performance of their duties, especially by contact of their hands and feet with unclean things, had to be removed by washing these members when they entered the sanctuary, Ex. 30, 17—21; 40, 30—32. Two passages of the psalms refer to this custom, Ps. 26, 6; 73, 13. If an Israelite had touched the carcass of an animal or carried any part thereof, he was considered unclean and had to wash his clothes and his body. Lev. 11, 24—28. 39. 40; 5,2; 22,4—6. There was a baptism of those who had recovered from leprosy, Lev. 13, 6. 34. On the great day of atonement the high priest performed very carful ablutions, both at the beginning and at the conclusion of his ministrations, Lev. 16, 4. 24. The man who had led the scapegoat into the wilderness and likewise he who had carried forth without the camp the bullock and the goat for a sin-offering, were required to bathe their flesh in water. Lev. 16, 26—28. When Levites were consecrated, they were sprinkled with water. Num. 8, 5—7. 21. The priest and the two laymen that had prepared the ashes of the red heifer had to bathe their flesh in water. Num. 19, 7—10. There were also other ceremonial washings or baptisms, with which the Jews were familiar, Lev. 15, 1—29; Num. 19, 11—22; Deut. 21, 1—9; 23, 10. 11.
But the most interesting of the Jewish religious washings was the baptism of proselytes, who, after being instructed in certain parts of the Law, and having made fresh profession of their faith, were then immersed in water, after which they were considered full-fledged Israelites in all things. It is this ceremony to which the baptism of John, in its outward form was related.28)
Another interesting question is that concerning the difference, if any, between the baptism of John and that instituted by Christ. It must be noted, on the one hand, that there are many points of agreement. John baptized by divine command, Luke 3, 2. 3; John 1, 33; Matt. 21, 25; Luke 7, 30. His was a baptism in and with water. Matt. 3, 11; Mark 1, 8; Luke 3, 16; John 1, 26; 3, 23. It was, finally, a baptism unto repentance, for the forgiveness of sins, Mark 1, 4; Luke 3, 3. In all these features it agreed with the Baptism of Christ.
Nevertheless, there was a difference between the baptism of John and that of Christ. When Paul came to Ephesus and found certain disciples that had merely been baptized unto John's baptism, he baptized them in the name of the Lord Jesus, Acts 19, 1—16. The chief points of difference between the two baptisms are indicated in this passage. John's baptism is consistently called a "baptism, of repentance." It was administered to adults only, to such as confessed their sins, as had reached the age of discretion, Matt. 3, 6; Mark 1, 5, whereas the Baptism of Christ is for all people, including the children, Acts 2, 39. 41; Col. 2, 11. The Baptism of Jesus works and transmits the forgiveness of sins as a gift which has been earned; the baptism of John points forward to the winning of this precious boon through the redemption to be made through Jesus Christ. In short, the baptism of John was typical, preparatory, as was his preaching; the glorious fulfillment has come in and with Christ.29)