Some things to remember: the Constitution protects the rights of minorities. That is why we cannot vote to outlaw inter-racial marriage, to segregate schools, to prevent Mormons from marrying, or to forbid Jews to own property. And what the courts have said is that gay people have those same rights.
Americans overall are equally split on whether same sex couples should marry. Ironically, a strong majority of Roman Catholics approve of marriage. (data here)
And just remember, in 1968, after laws against inter-racial marriage were overturned, over 70% of Americans DISAGREED. Imagine the outcome if they had voted on it?
Why is it that Conservatives who so favor the Constitution, forget all about it when it comes to equal protection? It doesn't say, equal protection only for straight white Christian men.