The appeal of using the Bible to deny civil rights is obvious. It is a time honored practice. But the sweep of history is toward toward the rejection of such practices. You can rationalize your views however you like, and of course we are all entitled to our opinion, but you are not going to influence the sweep of history much in that way. It is simply a generational issue at this point. Once the current older generation is no longer voting, the numbers will change enough that support of same sex marriage will be pretty much universal. Racism was similar. Discrimination against women was similar. This is known as progress. You are not going to change it.
One definition of mental health is the ability to adapt to change. Consider that.