PLOT: supernatural female

MC was left at a church when she was a baby. I picture her having some sort of tattoo/birthmark/symbol on her neck that eventually means something. She's adopted & grows up with a normal family. One day she has an accident and she's just about to die when an apparition shows up and heals her. It tells her that it's not her time yet. She must first fulfill her destiny which begins where she was abandoned. She goes back to the church and as she's stepping over the threshold something weird happens and she can't go in.

My original thoughts were along the lines of a witch or something, but vampire fits more (since they can't enter churches), or it could be something totally different. Any ideas on this one would be greatly appreciated as I'd really like to use this.