How can I politely tell this guy I don't want to hang out?

He's gone to my church for a few years, but we actually first spoke to each other at a lock-in a few weeks back when he decided he'd follow me around all night. I was simply raised to be most friendly with people who don't seem to fit in elsewhere, but I never flirted with this boy. He isn't even the type I would hang around at school. After our first conversation, he suggested we hang out at his house, but I told him I've been distancing myself from all my friends lately for my own good (which is true). He later asked if I and some others wanted to come over for movie night, and I told him I was busy. Today he messaged again, asking if I wanted to hang out Saturday. All this time, he's been complimenting my FB photos... I can't just constantly say I'm busy, and that's rude. What do I say?