Bill O'Reilly was correct - the Bible is touted too often in opposing gay marriage. Not everyone believes in religion, though, and the Supreme Court is not weighing belief. To me, religion is a constant fallback argument for those who have nothing more substantial for the debate. Have belief, but do not make it the centerpiece. You cannot sway an argument with a person who is staunchly anti-religious using religion. You will lose; trust me, I'm agnostic. Facts win an argument. If you want to say gay marriage will raise national debt or something, then fine say it. But touting religion to people who do not believe cannot work.
The fact is that marriage is a bond between two people, not a contract with the government. When you take religion out of the debate, the argument opposing gay marriage falls flat.