It's hard for me to think that this guy is just being friendly! I'd say he has a crush on you, or even more. He'd probably like to ask you out. I mean, what guy would ask if you were at a concert, spend a whole day asking you questions, ask for sure are you going to camp, help you with work during class, and then keep staring at you and smiling? lol I mean, do you fish? Because you sure have caught him! As for being Christian, I think he likes that because he was also at a Christian concert, so I imagine he's a Christian, and he's looking for a girlfriend who also is. But I don't think that's why he's being friendly. Does he stare at every Christian girl in the school? I doubt it! But he stares at you. That means something. I hope you like him back because he's all yours if you want him!
Good luck! :)