I have grappled with this for some time.
As the forerunner of Christ, John the baptist was baptising people, preparing them for the coming of Christ. After Christ came, he was baptised and commanded his disciples to baptise converts in the name of the Father, the Son and the Holy Spirit.
It is believed that baptism is a physical washing of our sins (that may be wrong) and Paul said it symbolizes our being dead and buried with him and also risen.
I have this belief that after Jesus died and shed his blood, his blood does the work of washing sins away, so baptism is no longer necessary.
I still believe in the "being dead and buried with him...."