On my first trip to Pakistan, to meet for the first time the woman would become my wife, the person in the seat next to me asked my religion (usually the first question most Muslims will ask you after your name) and I stupidly replied that I was not religious.
The guy behind me took umbrage, and fancied himself a philosopher. For forty five minutes, I had my neck twisted around while I listened to an "argument" that boiled down to "If you're not religious, you can't know that it's not OK to have sex with your sister." (Yes, he used that precise analogy.) The argument is stupid. If as an atheist I already know (or believe) it's not OK to have sex with my sister, I don't need to be religious. If I don't already know it's not OK, then why should I adopt a religion just to tell me that something I think is OK isn't OK? If I don't know it's not OK, then my Muslim friend might as well have said, "If you're not religious, you can't know that it's required to rub blue mud in your navel."
It would be nice if this were just an isolated incident of a psuedo-intellectual dumbass on an airplane, but we see this retarded argument from all over the place.
Most recently we see the theistard Mike S. Adams make essentially the same sort of case; he rejected Christianity "because it would not have allowed me to continue getting drunk and high every night while splitting time between four girlfriends." At James blog, theistard and chickenshit coward Croath endorses Adams views: "It is true, though, that with atheism anything goes." In other words, an atheist has no way of knowing (or believing) that it's wrong to get drunk and high every night and split his time between four girlfriends. Of course, if true, the argument has no force: If an atheist truly doesn't know that all this is wrong, it would be moronic to adopt Christianity just so that something he believes to be good would be called bad.
There's a weaker interpretation of this argument, which is not quite so obviously contradictory: The atheist might guess or suspect that having sex with your sister, or getting drunk or high every night, etc. is wrong, but the theist knows it; knowledge is unobjectionably superior to guesswork or suspicion.
There's a persistent tendency in not only theistic philosophy but also in secular philosophy that belief held as the conclusion of a logical argument is superior to belief held without logical argument.
This idea is completely retarded.
Any statement which is the conclusion of a logical argument is only as well-justified as the premises of that argument, and the premises of an argument are, by definition, not the conclusion of a logical argument. A conclusion is no stronger just by virtue of being a conclusion, because conclusions are only as strong as the premises from which one draws the conclusion. The theist (and, sadly, many secular ethical philosophers) just moves the guesswork from the statement about morality to some premises about a god and what it wants.
A related argument is that atheists' "moral framework has no grounds for rejecting such behaviour. [Atheists] can only argue on pragmatic grounds rooted in personal goals." We can note the trivial contradiction, pragmatic grounds is some grounds, not no grounds, and recast the statement to the slightly more sensible, "An atheist has no grounds except the pragmatic to construct a moral framework."
But what's so bad about pragmatic grounds? Essentially, this sort of argument asserts that it's a bad reason (or, if we take the argument literally, no reason at all) to do something because we want to. The only good reason to do something is obedience, whether to some principle or, more often, to some specific person.
We inevitably find in such an "obedience" proponent, a person who wants to do something, but lacks the will or the ability. It's a fair bet that Mike S. Adams wants to get drunk and high every night, and split his time between four girlfriends, but he lacks the ability to do so. He's probably pathetically shy, got falling-down drunk on two beers for the first time as a college freshman, clumsily tried to molest the head cheerleader, got slapped down, puked in her shoes, and converted to Christianity because he was an utter failure at even the most basic, benign hedonism. He's afraid that he won't be able to satisfy a woman who likes sex, so I suspect he's married to some anhedonic "close your eyes and think of England" woman. Nobody likes this guy because he's a tight-assed pathetic loser, so he prefers to think that everyone hates him because he's a righteous man of God.
Christianity and religion in general not only causes people to be monumentally stupid, but all too often turns them into them into sanctimonious moralists, deathly afraid that some people might consider themselves — oh, the humanity! — free to have a good time, enjoy themselves, and do what they want to do. Worse yet, instead of being upfront and honest about their self-righteousness — and everyone who expresses any moral belief is being self-righteous — they hide their self-righteousness behind their ludicrous invisible sky-fairy. Feh. What a blight on humanity are these religious assholes.