Your argument falls apart on the assertion that homosexual relationships are not the same as heterosexual relationships. Aside from the gender of the parties involved, there is no fundamental difference between straight and gay couples.

Others have said this and it's worth reiterating here: If the government has decided to endorse the union of a man and a woman in legal terms, then it has no place to deny that same endorsement to people who wish to enter into the same sort of arrangement except with a person of the same sex.

At the heart of this issue is something that has far deeper implications than simply deciding who may or may not enter into a legally binding marriage contract. We are arguing over this issue because the government picks winners and losers here. If the government had no favors to grant, then no one would fight to make sure they got favors and others did not.

Quite frankly, marriage is a religious institution and no force of government should (or could) force a religious body to change its principals to accommodate gay marriage. But so long as the government provides legal protections and favored status for one group of people in a marriage arrangement, it has no right to deny those same protections to another group.

I am an atheist and my wife is an agnostic. We assign zero religious / moral weight to our marriage beyond what we define for ourselves. Ours is a human relationship based on love and mutual benefit. We went through with marriage in the official sense only for the legal protections involved in the transfer of our property and the care of our children and to take advantage of certain benefits involved in taxation. The entry of the state into our relationship was not at all necessary in a practical sense. But it made many aspects of sharing property and raising a family infinitely easier.

My wife and I, non-believers both of us, are in a loving relationship that has only secular recognition. To many religious believers, my marriage is just as meaningless as a homosexual marriage. However my wife and I are receiving the benefit of state recognition of our union with none of the religious mumbo jumbo thrown in. In fact, we wouldn't have even gone through the trouble of state recognition were it not for the legal protections derived from doing so.

My marriage is exactly what gay people want. And it's incredibly unfair that my wife and I should be able to enter into this arrangement and others should not simply because of their sexual orientation.

Religious groups can now and will always be allowed to do as they please despite the best efforts of our current president and his minions. But to allow people like my wife and I to have legal protection of our property and custody rights while denying those same rights to a couple of the same sex is completely immoral and un-American. And until the government decides to stop granting favored status to marriage, it should stop withholding that protection from an entire segment of the population.