Rubi - I'm gay too. Your brother will be gay whether or not your or anyone else approves of it. Sure, you can "control" homosexuality by not having sex, but he will always be (and probably always has been) attracted to guys. He won't be able to control those thoughts any more than a straight person thinks about the opposite sex.
Your brother badly needs the love of his family. His decision to come out to you all was probably the hardest in his life. I repeat, it was the hardest decision of his life.
Are you going to base your decision on whether or not to love your brother on someone else's theological opinion? He is what he is, and it's not his choice.
I dated girls too just to try and fit in. He did the same. Now he is allowing himself to be himself.