The Greek word for baptize is “baptizo” – which “means “to cause something to be dipped.” This is one of the reasons we immerse, or “dunk”, when we baptize. Also, this is the clear Biblical pattern for water baptism.
Baptism in itself has no saving power. There is no magic in the water that we use. It is the same kind of water that we drink and the same kind that we bathe in. The purpose of water baptism is that it identifies us openly and publicly with the death, burial, and resurrection of our Lord (Romans 6:1-5). Our story ends, and the story of Jesus within us begins.
So, baptism is an outward expression of what God has already done on the inside.