Quote Originally Posted by Rhyfelwyr View Post
Paul said "Christ sent me not to baptize, but to preach the Gospel". (1 Cor 1:17). Yes he baptised a couple of people, however note how he also says he is glad he didn't baptise any others. Most importantly, those that he did baptise were Jews, so their baptism was in keeping with the way in which early converts from Judaism kept their Jewish traditions. Paul did it for the same reason he had Timothy circumcised... so that he might be a Jew to the Jews, and a Gentile to the Gentiles. We don't give that as proof that Christians ought to be circumcised, so why do it with baptism?

Also I think John 3:5 is symbolism, again looking to the example of Hebrews... the idea of the living water and never thirsting again.
God gave an ordinance to Peter to baptise the gentiles in Acts 10. Baptims replaced circumcision as the mark of the covenant. 300 years later the Council of Nicea determined that baptism with water in the name of God the Father, Son and Holy Ghost was necessary in order to enter into full comunion with the Church; they also determined that the act was effective even if the baptising priest was an Arian heretic.

Irrc the Sunday thing came in around 200 AD when Christians began celebrating the Resurrection rather than the Sabbath.