I doubt your son wants you to accept and/or fully embrace his lifestyle, he only wants you to try to understand it better and by doing that, hopefully, you would be able to embrace him fully, too.
You think that your son's homosexuality is in the same category as being a thief or a murderer or a child molester? Thats just ignorant!! Where have you been? Being homosexual isn't a felony, its not even a misdemeanor, its no where near a crime!!
Lets just assume that your son is one of the 30% of homosexual people who weren't born homosexual. Now tell me, exactly what is the difference? He is still a homosexual.
I hear you saying that you feel gay people make a big effort into promoting a gay lifestyle and defending it. Personally, I haven't ever met a homosexual person who "promotes" their lifestyle and I don't know what you mean by that, but as for defending the lifestyle- every homosexual person has probably felt as though they had to defend themself at some point in their life, thats because they are so often under attack by judgemental people like you!! So your son wouldn't have to put so much effort into defending his lifestyle if there weren't so many people in society who bashed it.
Have you asked your son why he feels he is gay? You said in your post that gay people should spend more time finding out why they feel the way they do about the same sex.. do you even know if your son does know why he is homosexual? have you had that talk with him?
I don't think that Christians hate homosexual people, you are intolerant of people who arent like you. Its not about hate, its contempt. Contempt for your own flesh and blood...