People have been having same-sex relations as long as there have been people.
Tell him the Bible says a lot of things that people ignore. They eat shrimp, they get divorced. Let him know that what he's been taught about the Bible is one-sided, and there are many ways to interpret it. The Bible is certainly not the only source for spirituality, anyway. If he chooses to continue to go to church, there are some denominations that would welcome him. The Episcopal church, for one, seems to be full of people who are very accepting.
Tell him he shouldn't lose sleep over this. There's nothing he can do about it; there isn't any choice in the matter. Whether he's straight, gay, or bisexual, he's going to have to accept it and just be the best person he can be.
Tell him that the people who love him will love him regardless. Some people might reject him, some will be accepting, and some people won't like it but they'll eventually come around. He should surround himself with those who love him and stay away from those who judge him. If he treats others with respect, he'll get respect in return.