From someone who came from a similar circumstance: do not pass go, do not collect two hundred dollars, go straight to punch him in the God damn throat. It doesn't matter who he is, or what religion he has, or what his own relationship to your mom is, he has no call to tell you you're not welcome in your mother's house. And if he is such a pompous ass that he's going to judge you for a nose ring then you need to make it clear that he needs to stay the hell away from you. Trust me. Get this out of the way early. When a step parent is this much of a dick right out of the starting gate, it's only going to go downhill from there.

Object to their marriage.

What would Jesus have done? really? because of a tiny piece of metal in your nose? God doesn't give a ****, this guy apparently does though.

That's hateful and mean of him. Unfortunately you won't be able to convincec your mother that marrying him is a mistake - she'll have to realize that on her own. Just be there for her when she comes to her senses.

You've been living there longer than he has, you don't need to listen to him. I doubt all hell will break loose just because of a tiny stud.

What did your mom say?

That arrogant self righteous ass! I know the feeling.

If he ever gets mad at you, just always tell him that you've been deeper in his girl than he will ever be.

as a religious person i could care less about tattoos or piercings. who cares? they might call it religious.. just get out of there.