Well, are you going to break this news to Abraham, Isaac, Jacob, Moses, and the other patriarchs who practiced polygamy with God's approval? If you can cite any scripture where homosexual acts were practiced with God's approval, I might be willing to reconsider your moral equivalence, but until then...
The horse is already out of the barn on this issue. The Supreme Court decided circa 1890 the federal government had the right to regulate marriage when they ruled the Mormon's practice of plural marriage as a religious belief was not protected under the First Amendment.
If a Biblically approved practice of religious belief can be banned, where do the gays get the idea their behavior gives them a greater "right"?