First off, while it is true that more religious people wait until marriage, I think that it is unfair to assume that everyone who waits until marriage is religious. In fact, myself and my closest friends that did wait, or are waiting, aren't that religious or even consider themselves athiest. There are a lot of other good reasons to wait that aren't "because God wants me to" (not judging and saying for everyone those good reasons will weigh out the good reasons for not waiting, but my point is that there are other good reasons out there). And none of them are poorly adjusted (or whatever the poster said) people either.
I feel that someone who waits until marriage is showing commitment. Not saying people who don't wait are uncommitted or more likely to stray, just that someone who chooses to wait and will pass up opportunities because they are waiting to save it for the person they're going to marry, is a sign to me that they will be committed in a relationship and also have a strong sense of self worth and independence. They've probably been in relationships before were the other person has tried to pressure them to do it, but they were able to say that they wanted to wait. Once again, understand that I'm not saying that if you have sex before marriage, that means you're automatically going to cheat on your spouse or that you give in to pressure or that you have no self worth, just that I think those characteristics are present in a higher percentage of people who wait.
On the flip side, I think the people who want to wait, and then just speed up their whole courtship so they can get married and have sex just to say they waited are ridiculous.