I say no one should.
First of all, marriage is not about religion. It is a civil ceremony. There are a lot of people who don't believe in religion. Or, if they do, it is not the religion that follows the teachings of the Christian Bible.
I know a lot of you advocate that the government should stay out of people's lives. Why is this different.

I know homosexuality offends a lot of you. It doesn't offend me. But what if I decided that I am offended by an American marrying someone from Russia, or from South America? Can I move for a law or constitutional amendment stating that American citizens can not marry those from other countries?

Why is it the business of the government who should get married? The U.S. is supposed to be a free country. The government should not regulate morality.
We do have laws concerning age limits and behavior with animals. I am talking two willing people, whether they be same sex or different sex.

Please tell me why the government should interfere.