I think religion and superstition are psychological responses to the human mind's abhorrence of chaos and the need of intelligence to impose patterns and order on the world even if it isn't really out there. The idea of religion as a social stabilizer came later.

If we're talking only about the context of self-control, the answer is right there:

Religious lifestyles may contribute to self-control by providing people with clear standards for their behavior...

The idea of clear standards isn't something that is, or should be, confined to religions, but in our modern world, it pretty much is by default. Our social culture, outside of religion, seems to have very vague ideas of basic morals and principles, and most of it seems to break down into an ever-shifting set of values that renders the entire landscape of morals and principles "gray." We're wallowing in "if it feels good, do it," "who are you to judge?" and "nothing is black and white." On this Jell-O we are expected to build a strong society. Small wonder religion is attractive to people who otherwise feel rudderless.

Meanwhile, on the far end of the scale, we are facing societies with diamond-solid irrational certainties that can drive them to blow themselves up for the cause.

The answer isn't to simply adopt an opposing irrational certainty. It's for society to realize that it's possible to have rational certainties. Unfortunately, neither religions nor moral relativists are likely to get behind that. Given the remaining choices of benign religions, lunatic religions, or a situational moral vacuum, what's the least objectionable?