The issue of "is it morally right or wrong" falls apart because it is between two consenting adults. Anything beyond that, from a government perspective, is purely subjective and opinion. It does not matter if you believe it is dictated from God Almighty - that's not the government's place to decide.
Besides, this is a debate about gay marriage, not the morality of gay sex. The simple fact of the matter is that marriage is not a simple religious institution, and has not been for many centuries. The association of wealth, inheritance, insurance, property rights and the thousand other items that go hand in hand with marriage has made it a LEGAL institution.
You're well within your rights to say gays should not get married in your church. That's a private organization.
It is a different story altogether to apply those religious beliefs to the benefits conveyed through the marriage of two individuals. If you feel otherwise, then why can a judge perform a wedding? Why does it take a court to get a divorce?