I particularly like the sin of Predestination:
Predestination. I've had a few one-on-one conversations with creationists, and one of the weirder but fairly common discoveries is that they reject the concept of chance. Everything must have an intentional cause. A branch fell off my tree because the wind blew it down; similarly, if an ancient ape evolved into a human it must be because…? They've filled in the ellipsis with "God", and they are not satisfied with explanations that do not invoke causes and intent. Try it yourself sometime; they have an almost allergic reaction to the notion of junk DNA, for instance, because there's no way molecules could have a random element, it must all be for a purpose.
This trait isn't exclusive to religion, of course; you can see causality built right into the structure of our language, and it's probably hardwired into our brains. Religion makes it difficult to oppose, though, because it provides a convenient catch-all repository of causality: god did it. It doesn't matter that it's a meaningless phrase, it seems to satisfy an intrinsic desire to wrap up loose ends with an explanatory purpose.
Some of the comments are also quite insightful, and one links to this related article.