Does anyone think that gay marriage somehow threatens traditional man-woman marriage? The thing that threatens heterosexual marriage most is boredom.
The entire "issue" here in the United States now is the fact that our Nation does give benefits based on a contract called Marriage. Our Federal Government should not even be in the business of marriage in the first place since the majority of the benefits given for marriage is to just promote and encourage a specific lifestyle which they deem "the best". To truly live in a free country would mean that any particular lifestyle that you choose to live should not get punished nor promoted by the Government.
But the fact that our government does give entitlements towards 2 parties that sign under a marriage contract, then they have to allow for those same entitlements to every single adult US citizen regardless of race, color, sex, sexual orientation, religion, ect. Otherwise something like the DOMA is Unconstitutional since not all men are created equal when it comes to federal recognition of marriage.
The churches can still discriminate all they want if they choose just to marry opposite sexes or just marry white people for that matter....... as long as those churches also don't receive government entitlements/breaks themselves. But on a federal level they have to give the exact same rights to all adult US citizens period.