(i) The baptism of Jesus as the basis for Christian baptism.
Jesus is baptised by John in the Jordan (Matt. 3:13ff.). The Baptism of John was a polemic against the Jews who assumed that they had standing within the Kingdom of God by virtue of their circumcision. Proselyte baptism of Gentiles was on the basis of their non-circumcision. Thus, for a circumcised Jew to be baptised by John was virtually to say that one was an ethos in the eyes of God!
Behind the motif of proselyte baptism lies the powerful theology of participation in the Exodus event, the crossing of the Red Sea, and the sanctificatory cleansing in the establishment of the Sinaiatic covenant. So when Jesus is baptised as the Messiah of Israel, as the second Adam, it happens at Bethany on the other side of the Jordan, where John was baptizing (Jn. 1:28). It appears significant, at least to me, that the Messiah, who was in himself, as munus triplex, the whole of Israel incarnate, had to leave the land, and then return into the land through the waters of the Jordan. Is it possible that he was calling his people to leave the occupied land also, that they may re-enter the land as the true and free people of Messiah, not only as an eschatological sign, but in the time and space of the first century world?
For a Jew to be baptised was a blow struck at the heart of the security claimed by adherence to Mosaic law, drawing the Jews under the judgement of the law and driving them to repentance and hope in the One who baptises with/by/in the Spirit and fire. The baptism by John had its counterpart in the cleansing, and/or, judgement, of the Temple by Jesus in preparation for his propitiatory sacrifice as the Lamb of God, a cleansing which points to the sanctification of the Church. For Jesus to submit to John’s baptism was an act of obedience and hope through which he drew his own humanity into the judgement which the law demands, and offered up through that humanity the obedient response in hope to the Father. In this sense, Jesus’ baptism by John was substitutionary and was completed in his baptism of blood on the Cross when he died as the representative of all humanity, both Israel and non-Israel. And in baptism, the Church binds itself to the covenant and the Heilsgeschichte of Christ. Furthermore, Jesus, as the baptised one who baptises with the Holy Spirit (John 1:33) continues the work of his own baptism through the Church.