An article on the gay marriage wars|
Yes, most of the arguments are religious ... which makes it difficult to have a conversation. Attempting to translate them into a purely secular argument ... well, is likely to be unsatisfying to either participant in the conversation.
To your second question ... the primary argument is the religious one; God has endorsed heterosexual marriage and condemned homosexual activity, so any legal endorsement of gay marriage endorses sin. Outside of that, the question becomes ... if marriage isn't between a previously unrelated man and a woman, what is it? Slippery slopes come into play. Can three people form a marriage? Can I marry my sister, or my mother, or my grandfather, or my daughter? If all of those are acceptable, what's the point of having legal marriage structures at all? Where do you draw the line?
It seems to me that much of what proponents of gay marriage want can be achieved by other means ... durable powers of attorney, for example. Those sorts of things seem reasonable to me. But I don't think you need to re-define what "marriage" means to get some of those benefits.
As to the first question ... again, I think the question has mostly a religious answer. If you're introducing a child into an environment in which "sin" (however you may define it) is embedded in the family structure, is that better for the child than leaving them in foster care? It's a matter for reasonable debate ... assuming you accept the religious premise of the argument, of course.