does the Pastor know you're Wiccan? if they do and they accept you for it, then it's no big deal really. if you haven't told them, you need to, you can't base a lifetime on a lie.
it doesn't matter if you're in the same or different religion, as long as each other knows and accepts it to some degree. my cousin knows i'm Wiccan, she recently married a man in The Salvation Army and they're training for the ministry. the two of us haven't changed. [well, she's extra holy, but she doesn't tell me i'm doomed to hell or anything] if you're happy and this person knows who you are, then there's nothing wrong in dating them.