I have previously re-defined religion and spirituality as, “The worship of one’s own inadequately explicated emotions and proprioceptive sense.” Note that by “worship” I mean misplaced/misdirected euphorias locked in self-perpetuating ignorance-states.
Religion is a kind of structure in the ideas which reaches into feelings, a kind of relation between the two. Society gives us these forms, and many different ones exist. They can be functionally defined based on their effects in terms of one’s psychology, how they affect the nature of the believer.
I would argue that religions do not exist because they have any relationship to real or perceived events, conditions or causes in our experiences, but rather solely on the basis that 1) a person encountered a particular religion-meme-structure at some point, and 2) this structure became efficacious to him on a social and/or psychological level, and therefore was adopted into the mind.