Just say hi! Or ask her to let you borrow her bible, And say something like, "I like your bible, where did you get it?" And take it from there... or are you more in the situation where you've stopped talking and you wanna talk to her again.?
Ask her; Did it hurt? and when she asks; Did what hurt? Your reply will be; When you fell out of heaven. I wish I was a christian just so I could use that opening line inside of a church, would be epic<3
Seriously though, it should be pretty easy since you know she'll be at a certain place. Just walk up to her and give her a little compliment about her shoes. Or maybe ask her if she's hungry and wants to go for a bite after church. All you really have to do is gather the courage to step up to her and say something, anything. Should be automatic pilot after that, if it's mutual.