Anthropologists believe that religion started when humans reached behavioral modernity, which is when we started to do things like abstract thinking and rituals among others. Other things that helped humans be able to come up with religion was increased brain size. An important part of the brain to make up symbolic things and a religion is the neocortex and it is theorized that it tripled in size during our evolution. Religion may have helped strengthen the relationship with one’s social group. Interestingly, some theorize that tool use contributed to the development of religion, saying that tool making required abstract thinking, as one has to imagine the tool and it’s function before hand. Causal beliefs help form religion, as cause and effect scenarios are part of religion. Language also plays a major role because one needs language to spread and create organized religion. Religion needed language to evolve to happen on a larger scale than individually. A thing that may have spurred religion on, as opposed to mental components needed to create one, is morality and what is best for the group. In social groups, members must all work together and help each other. Religion creates guidelines, so group members are treated fairly and the whole group can benefit off some of religion’s laws. In Christianity for example, it has rules like not stealing and not killing, great for bringing order into a social group.
Psychologist Matt J. Rossano argues that religion emerged after morality and built upon morality by expanding the social scrutiny of individual behavior to include supernatural agents. By including ever-watchful ancestors, spirits and gods in the social realm, humans discovered an effective strategy for restraining selfishness and building more cooperative groups. The adaptive value of religion would have enhanced group survival. Rossano is referring here to collective religious belief and the social sanction that institutionalized morality. According to Rossano’s teaching, individual religious belief is thus initially epistemological, not ethical, in nature. (Wikipedia)
Religion, or at least symbolic rituals and spirituality probably emerged in the paleolithic. Burials and monuments (like Stonehenge) are evidence of some type of spirituality. Religion seems to be part of human nature now. Every culture created it’s own religion at some point, or adopted another’s. Humans as a species are naturally drawn to religion and spirituality in many ways despite a few who personally aren’t.