Christian marriage is a population thing, just like opposition to birth control is a population thing.
I'm afraid you are wrong on both accounts. As I said before, this is about God, and what He has chosen marriage to be.
Ah, I wasn't being very clear. I don't doubt for a minute that straight marriage is one of the tenets of your religion. I was just trying to offer an explanation of why so many religions have that as one of their tenets: because if there ever had been religions that didn't promote widespread childbearing, demographics would cause the religions that did to swamp them. (Families have always been religions' best training schools: even today, when migration and evangelism mean that in most Western cities finding a new religion is no harder than finding a new brand of toothpaste, the overwhelming majority of religious people have the same religion as their parents did.)

Peter