Being Gay is choice
Being homosexual is as much a choice as you are attracted to the opposite gender. Did you ever consciously decide for yourself, "I'm going to only feel attraction to females?" because I sure didn't. It's not a choice. Yes you can -choose- whether or not to participate in homosexual/heterosexual activities regardless of attraction, but that's ignoring the issue.
Being religious is a choice.
Having a belief is not a choice either. You do or don't. Participating in religious activities is, again, a choice.
What you are saying is that it is wrong to be anti-gay
Being "anti-gay" is as unnecessary and illogical as being "anti-cheesecake" or "anti-red t-shirt" or whatever. It's a personal choice that is based on a preference which is not consciously determined nor correctable and causes no harm to any non-consenting parties. There is absolutely no reason to be anti-gay other than irrationality.
If they don't like it then that's their right.
They can not like it all they want, and no one cares. What matters is that they're trying to impose that onto others and impede the rights of others in their beliefs.
You can't sit here and say that people's opinions are wrong.
Yes I can, and I am doing so. Opinions aren't some magical no-go zone where everyone is always right in happy fun land. You could hold the opinion that a blue helmet provides more protection than a red helmet and I would call you a fool. There are subjects where there is no 'right' opinion, like preference in aesthetics or taste, but this isn't one of those areas.
Then you are just as worse as them.
Let's look at this comparatively. Anti-gay groups are trying to stop the legality/social acceptance of homosexuals. anti-anti-gay groups are trying to stop arbitrary bigotry advocated by said anti-gay groups. Who's just as bad as who?