John 3:3 and 5 says it all and really needs no explanation = heaven is opened and it is by belief and expectancy that we enter imho - twinc
as for belief coming first = this is a sham for who certifies or verifies that we truly believe = according to Jesus it is very difficult if not impossible for adults to simply simply believe = hence a very strong case for baptism as children who will simply believe - so water may and should come before certain belief which mostly never comes - twinc