It's difficult to portray any type of serious interest in that kind of setting. First off, is this someone who is near you who you'd actually be able to meet if it does get to that point if that's your intention? If it's just someone Instagram famous it's not really going to be worth the effort. But you never know if you don't try!

For conversation purposes, I'd just build off your similar interest. Does she have videos on her account drumming? I'm going to just assume she does, so maybe compliment them and express that you enjoy it as well. I'd give a horrible example so I won't, BUT I do know at least for myself being the recipient, by including a question of some sort with your comment/DM you're asking for a conversation to happen. It's not just stating you think she's attractive which isn't asking for a reply. You can read that and move on or get a thank you but then where do you go from there and that's the creep thing you want to avoid. Asking her a question would give her an easier, more direct thing to respond to you with which I think in turn would make an extended conversation more likely than otherwise. Then you just build off her response if she gives one. Don't feel bad if she doesn't answer, I'm not trying to be a downer but if she has 7K followers, she may not respond. And that doesn't mean there aren't other Christian girls that like the drums out there. They just don't have that many followers and are as easily accessible.

I hope some of this helps a little, I'm sorry if it doesn't. I do wish you the best of luck! Never doubt the possibilities.