Well, I think it's best to just let sleeping dogs lie, e.g., it's probably healthiest for both you and her to not socially engage (unless it's on her own initiative).

It sounds like it's an established clique, that's all. It would be nice if they included you, but they haven't. I'd try and move on from the entire thing. Who knows, maybe they aren't that fun to spend time with, anyway.

If you find that it continues to bother you, I recommend you start fresh at a different church that has a lot of members your age. Have your transportation pre-arranged - it complicated things at your current church. It will be easier to make new friends if you don't rely on them for a ride.