Why do humans believe there is something greater than themselves and accept the fact that somethings are beyond their understanding and let it be at that?
Humans for some reason, must provide an answer for everything, so god was contrived as a concept to provide answers humans could not conceive of...Thor god of thunder. Zeuz king of the gods, Aphrodite etc.. Christian god, creator, Jesus redeemer etc. Have you ever considered that god is not a deity but a concept within each person's mind whether you are a believer or not? The mere act of not believing in god is by choice an acknowledgment of god's non-existence.
People who claim being filled with the spirit of god including symptoms of oneness, wholeness, connectedness etc, have simply become aware of a different way of thinking than they are accustomed to, crossing from one side of the brain's hemisphere to the other, some call this enlightenment but it is only a different way of thinking. Christians are led to believe salvation is a product of accepting Jesus as lord and savior because that is what they are told to believe. They believe this without questioning the logic of this because of faith in the illogical. Faith is not logic it is a belief that convinces people it is truth without any merit of truth in it.
Ego death is the realization and awe of knowing you are a tiny but significant part of something greater than yourself.