If you go to the OCS website, you will find that they are definitely not the same as the "Christians" (in name only) who give unrepentent sinners a pass.
Well, the point I'm making is that being a Christian (calling yourself a Christian) does not preclude anyone from associating with gay people. In free, rational, developed societies people pretty much get to believe what they want without the fear of retribution.
The Christians at OCS have chosen a belief system that takes a dim view of gay people (for reasons aside from supernatural softball skills). And that's their choice. In many, many countries they wouldn't have that choice.
Also, whether their dislike of gay people is based solely on their Christian beliefs is difficult to say. For those who holds their beliefs as a central part of their lives, belief and emotional stuff is tangled up together in one ball. However, I suspect that even if they were not Christians, they still wouldn't be keen on the whole gay thing.