Sorry for the necropost here.
Yes, it can be very difficult to have an atheist group on campus. I'm the treasurer for an atheist group at NIU, not too far from the SW suburbs. We are constantly having our fliers torn down, chalkings defaced, etc. Some of us in the group, like the girl who founded it, thinks this is a good thing because it means we're getting people thinking.
Anyway, good luck with your group. I like your "Holy Rape" idea lol. You should come visit NIU and our group, we'd love to support you in your efforts! Message me if you're interested.