Religions, according to the basic argument of sociobiology, are early and, for millennia, successful protective systems tied to the potentialities of the brain and body, and the necessity for survival. Their success allows them to give people confidence and security, so that they can explore their own natures, society, and the world around them. This exploration, characterized by a high degree of intensity and comprehensiveness, is known as religion.

Religious beliefs and practices can be divided into three broad classes. One class includes belief in a creator god that watches over humankind; in immortality or life after death; and in the possibility of an ultimate meaning to life. Another class includes belief in special deities that emerge as guardians or protectors of their clan or tribe. The final class includes religions based on totems, or objects or animals that assume the spiritual role of unifying and ennobling a clan.

Surveys show a strong correlation between what people say they believe and the way that they behave. So, for example, people who say that behaving in a certain way is essential to their religion are more likely to do so on a regular basis. However, it is important to note that the vast majority of people have no religion. Religions do much more than protect and transmit the means to attain the goals that are most important to them. They also help people recognize the many different kinds of limitation which stand across the project of their lives and how to deal with them.