Don't ridicule the person, ridicule the argument. This thread seems to be all about poking fun at atheists, but it would probably be best to single out atheistic beliefs as opposed to the people who share those beliefs. After all, they're in a rather serious situation. Atheists aren't a joke, they're a tragedy. It would be best to treat them as such and pray for them...
To use one word to describe one, I'd say...
"Lost"