Well for example the whole mentality that mankind is 'fallen' and tainted at birth is one example. If you profess to believe that, or worse, believe it, then you'll live as if it were true. Another example that is very popular among fundamentals is the belief that the world is somehow getting worse, or armageddon is near, or other similar beliefs. I can't see beliefs like that benefitting humanity in any way.

Not to turn this into a debate thread, but I must disagree with you. I think that if you name the problem, then you're better equipped to overcome it. To draw a comparison, people that go to AA meetings are first encouraged to admit that they are alcoholics. If they don't admit they have a problem, then they're not willing to try and fix it. Similarily, if you believe that you're ultimately a good person, then you won't feel as much need to try and fix or avoid your bad tendencies, because you'll use the excuse that "I'm a pretty good person. I don't need to change." However, if you recognize that you're tainted by sin, then you'll think "I know I'm not a good person, but I'm going to try my best to be as good as I can."

Now, where I see that quote as having some merit is in things that have been named evil by certain christian organizations, that have no grounds for being considered evil (birth control, for example).

Quite true. How are you supposed to find a solution if you don't understand the problem?

But what happens if you impose a problem on yourself that isn't really there? You'll devote energy toward finding a solution to a problem that doesn't exist, and in the process, you'll only frustrate yourself when you can't solve the problem. (Let me know if you know of anyone who can solve a problem that doesn't exist - it might come in handy!)

Just ask an anorexic about that.

yeah, that's kind of what I'm saying. But I think it's safe to assume that people are generally inclined towards evil over good. Hence the need for laws and government.

Like I said though, the way I see it, the problem that quote brings up is that sometimes we (christians) make it more complicated than it needs to be. Like, "OMQ, THATS BAD! WE HAVE TO STOP" when it's not really bad at all, and thus we feel bad about ourselves with no reason.

In addition to the example I provided with birth control, consider masturbation. Probably 99% of christian organizations will say it's bad, but if you read the Bible, it's very difficult to find evidence to support that it really is. There's a few passages that if taken in a certain context may suggest that it is, but maybe we're just looking for problems that aren't really there.

Other examples include:
Alcohol consumption
Smoking
the death penalty (accepted by most christian organizations, but not all)
there's probably more, but I can't think of anything atm.

Now, for the record, I'm not taking a stand on any of these issues to say they're good or bad. I'm just saying that they're kind of a gray area. I personally don't think there's enough evidence to say for sure one way or the other.