If people support gay rights....?

So, i really don't understand this. So, if you are a person who says you believe that marriage is between a man and a woman and that ity is a sin and being gay is a choice, you get hated on by everybody and you are called a bigot. Yet, why is it that only a small number or states allow same marriage, and only some states allow gay adoption and why is it such a big issue? because apparently, if you disagree with it, you are marked a hater. Then why isn't it legal EVERYWHERE?