Someone might have power to force someone to do something, but this does not mean they have the authority to enforce their command.
For example, the Nazis had the physical power to force many Jews into concentration camps, and did so, but of course they did not have the authority to do so.
So where does authority come from? The shifting opinions of people certainly does not decide. If someone believes in majority rule, what happens if I'd convince most people that majority rule is wrong?
Ultimately the only firm foundation for anything is the Bible, God's word. In Romans 13 the Bible says that "there is no authority except from God." Authority does not originate from people. It comes from God.
When the courts rule that homosexual "marriage" is legal, does that make it right (or even possible)? No. God already ruled on the matter. In Mark 10:6-9 Jesus said:
“But from the beginning of the creation, God ‘made them male and female.' ‘For this reason a man shall leave his father and mother and be joined to his wife,‘and the two shall become one flesh’; so then they are no longer two, but one flesh.“Therefore what God has joined together, let not man separate.”God said it. That's all there is to it. It doesn't matter if you believe it.
Murder did not become right when Hitler said it was. Murder did not become right when the American Supreme Court said it did. Homosexuality did not become right when the American Supreme Court said it did.
How exactly should the government be structured? What does the government have to do with marriage, if anything? Those are questions worth answering, but that's not the purpose of this post. I don't have all the answers, but I know Someone who does.
What is the point of this post? To affirm that God rules. His rule is ultimate. There is no right and wrong unless God decides. That's all.
Oh, and let's pray :)