I'm sorry, but I doubt the often-made claim that religious ideas come from unexplained phenomena.
Simply, no human beings sees the unexplainable and automatically assumes that a deity did it. Sane ones don't anyways. And they certainly don't convince others of it either.
Religions, save for maybe Greek mythologies, don't claim that the reason for X is God, that the reason for Y is because of demons, that the reason for Z is because of <insert religious idea here>.
Usually, the belief comes before the phenomena due to some type of charlatanry and only later does the charlatan either create situations that seem to prove his point or point to things that he feels may prove his point.
Do you have an example of a religious idea that people held because of a natural phenomena that cannot be more reasonably attributed to a preexisting belief or superstition that was only later incorrectly verified by un-scientific means?
You use demon possession. What human sees a person with epilepsy and the first thought is "it must be demons" unless the person already believed in something like demons and demon possession?
Chances are that the person already believed or was superstitious about demon possession and upon seeing the epileptic and not knowing what it was attributed what they saw to what they already believed.
The point I'm getting at is that most religious beliefs don't stem from phenomena we can't explain. If that were true, most people today would believe in religions becaue of unexplainable phenomena. The fact that the majority of the world's population claims some religious belief has nothing to do with unexplainable phenomena but with a hope that provides comfort. Normal sane human beings see an epileptic seizure and, if the idea isn'talready present in their head, demonstrate concern about the medical health of the person. I believe this was probably the case even back in older times.
Little suzy has a seizure, mom and dad are concerned so they take her to the priest, who in this time we're talking about is also the primary medical provider. The charlatan of a priest says "She's possessed. If you do X, Y, and pay money to the church she'll be saved by this super magical remedy I have." Mom and dad then go back to their friends and family and say that the guy who is supposed to be an expert (who, if he has a cure, is able to "magically" heal little suzy by some means he most likely kept hidden from them) said it was demons. Phenomena occurred, those who didn't know went to someone who they thought would, and that person lied for personal gain.
That fits in so much more accurately with the human nature I know than the lesser evolved species you speak of who fear all unknown phenomena and who all of a sudden create ideas like demon possession and mythical gods out of the blue to explain these phenomena, while going on to be ever so successful at convincing others, no all the rest of society, that their folly is true.
