Cal: These terrorists based their actions on ancient documents, an imagined afterlife, and the pronouncements of men imbued with religious authority. (I can't think of a much more uncritical and irrational approach to belief.)
And likewise, Christians who oppose homosexuality basically use a "because He said so argument."
When I mentioned divine commands in the last thread, I was rightly corrected by two commentators who pointed out that the case against gay marriage typically comes in the form of natural law argumentation rather than divine command argumentation. People on this issue don't typically just say "because He said so." I brought up divine commands because
I remember when I went to groups like Campus Crusade for Christ, where very often speakers (such as Josh McDowell) would make a case against premarital sex. The argument was almost never in the form of "God said it, I believe it, that settles it." Nor was hell threatened. There reasons presented always had to do with achieving stable happiness on earth.
That doesn't mean that arguments were all necessarily or equally good. But I think atheists are sometimes naive about what kinds of reasons religious people have for what they believe.
A good friend of Bob's and mine from college days, Bill Patterson was an atheist. He also gave some of the most forceful anti-abortion arguments I have ever heard.
The arguments against SSM typically take the form of natural law arguments. I suppose you could argue that these are implicitly religious, in that they appeal to the idea of inherent purposes which materialistic atheists might reject. But it's very far removed from "God said it, I believe it, that settles it.
Here is an example.