As for beliefs, obviously there is a lot that doesn't stand up to rational scrutiny, though like in any long-standing tradition, many things that may seem irrational or backward are in fact closer to reality than various modern fashionable beliefs. (Clearly, a simple blog comment can't do justice to this topic.)

I'd recommend Nick Szabo's essay Objective Versus Intersubjective Truth as a good first explanation of the topic.

Note: The website appears to be down at the moment, Google cache available here.