It would be wonderful if the government didn't have a say in it, but there are too many legal situations in which being able to say you are "the spouse" becomes important (estates, taxes, and medical are just a few that come to mind); therefore, government does have to be involved.
Look, I have had homosexuals in my life since the day I was born. These are people I care about and love. These are my friends and my family. My aunt was a lesbian who was murdered in her own kitchen by a young man who wanted her dead simply because his mother loved her. A gay man was the father figure in my life for many years before my biological father became an active part in it. He loved me and cared for me and taught me about compassion and self-respect more than my own parents did. My two best friends in my adult life are gay men, one of whom I love and respect so much that I chose him to stand up with me when I got married instead of having a Maid of Honor. He was my Man of Honor, and he embodies that role more than any heterosexual man I know.
These are our fellow human beings. I love them. I will not believe that the God I believe in finds them unloveable or unworthy of His grace. I do not respect those who call themselves Christians, then willfully judge and discriminate against them. I do not respect a government that persists in denying upwards of 10% of its populace basic legal rights that 90% of the populace has just because they are heterosexual. That is no better than denying rights based on color of skin or religion or gender.
I can only align myself with that which I know is right. I teach my children to do the same. If my generation can't get this thing right, I can only pray that their generation will.