There is a little/some evidence that circumcision can have health benefits. But millions and millions of men around the world are not circumcised and have had no issues (I mean, that's how they came into the world, so surely God/evolution/Cthulu/Flying Spaghetti Monster may have an idea of what the foreskin is for). And the foreskin is very sensitive, leading to more/better sexual pleasure when he grows up. So circumcision is not necessary. Ask parents why they had their son circumcised...if they didn't do it for religious reasons, then they likely did it because "daddy is circumcised" or they don't want him to be teased after gym class.
There are proven health benefits to vaccination, appropriate medicine, etc.
As for religious stuff...expose him (or her!) to all sorts of religions and let him (or her!) decide.