how come gays can talk about it but we cant?

How come gays can speak out about how it is alright to be gay, but yet i cant say anything about saying being gay is bad? I believe it is equal somebody that is not gay gets judged or something for speaking there opinion. But it is completely fine for a gay to say something. That is not right at all i dont believe that being gay is that right life style, just because i dont agree with there lifestyle doesnt mean i hate them. But i will tell them that i dont agree with it if they were to ask me. But that does not mean that i will not be friends with that person. I have quite a few friends who are homosexual. I dont have nothing against them, i just dont agree with there lifestyle. But it is not my life it is theres. But i still feel that i have a right to speak out against it and not be fussed at by a teacher.