Why Religion Exists This is a super simplistic view. All 'religions' stem from specific instances of alter states of consciousness. Experiences in these states are felt as being more real than what was previously regarded as reality.
It is from exposure to these experiences that all religions developed. The question of why religion exists now in its current state has clearly branched off into many areas. The fundamental features of all religions orbit these experiences though.
What they are and how they alter out perception of reality is a more important question for me personally. Although it is interesting looking into the various lines of inquiry into how religion has manifested in different environments and how it has adapted to social needs.
What we call 'religion' today has inevitably sprung forth for a variety of reasons including animism, memory, literacy, population explosion, etc.,. The list is almost unending. The very concept of God is of no real significance to some 'religions' whilst being at the heart of others (eg. Islam and Daoism/Taoism). Confucianism is also loosely defined as a 'religion' in modern parlance, yet God is irrelevant. Many traditions in Buddhism have no concern with Gods either.
Also, some cares more about 'souls' and other far less so. The same goes for a whole array of views surrounding religion, such as afterlife, rebirth, scripture, ancestors and connections to nature in general.
The only common feature I have found is in traditions that involve altered states of consciousness, initiation and mnemonics (lost mostly through the advent of literacy).