I honestly don't know what to tell you because I've never been in your situation. Personally if you're still in highschool and he's in college, I'd find it easier to be more worried about him going off to school and meeting new people than what kind of ritual secrets he may aquire in the next semester.
But that's just me.
I'd say just be supportive and if it really gets to you, you can either explain to him where you are coming from, except it, or move on. It's just something you're going to have to deal with.
Hope that helps (hope that doesn't sound snotty either).
Hootie
Hybrid Mode
