Hell, my high school (grades 7-12) had around 200 kids and atleast 50 of them were pot smokers. I doubt that you will have any trouble in finding some tokersin your school.
Generally a Christian college is really just Christian in official name and such and maybe in religious classes it offers. Generally it's still just college as usual. I don't know though, I've been to ones here like Sacred Heart university and it's just like any other college in the state, but I'm not sure exactly how true the stereotypes of religion in Alabama go.
Don't know what you mean by Christian....seems to me, the more loudly someone proclaims their Christianity, the less likely they are to deserve the title, and I know some right-wing kooky Christians who don't consider Catholics to be Christian. Would your parents see Notre Dame as a Christian school? Edit: How 'bout Brigham Young University? I attended Millsaps College, a Methodist school in Mississippi, and I smoked with faculty there.
My dad's a Catholic and he's been smoking weed ever since the mid-sixties! Edit: He does, however, give up marijuana & alcohol for lent, though.