Was I right to tell my cousin to stop being Shinto and Wiccan because for all I know she might be insulting to somebody else with it?

You are entitled to your opinion. Your cousin is entitled to her opinion. Neither of you is entitled to impose your opinion on anyone else. To do so might cause offence or worse.

You were completely wrong.

Not your cousin YOU with your religious intolerance!!!!!!!!!

You just have to be a pretend Christian proving why people like you not only drive people further away from God but are the reason so many DECENT people are becoming ANTI THEISTS!

Depends . Did you manage to not be insulting to your cousin ?

You need to change your name because all the other Andrews may find it insulting that YOU share that name too.

You can disagree/disapprove of a persons beliefs... but you don't get to tell them what those beliefs should or shouldn't be.

Not only were not RIGHT to tell her that, but you were also ignorant as hell. No one can just DECIDE their beliefs, they FEEL their beliefs. It would be like me telling you to stop preferring chocolate to vanilla, assuming you did prefer chocolate to vanilla. You can't stop your preference just because someone told or asked you to.

were you right to tell another human being how to live their life? No.