There is no doubt that religion has been promoted by power brokers to provide the illusion of a good outcome for the poor and downtrodden. Islam has gone one better by promising an afterlife that is filled with forbidden pleasures.

The relative decline of Christianity may be a result of better education but modernity has provided a quality of life that is arguably preferable to the ambiguous Christian version of the afterlife.

I would agree with you that we will return (more or less) to that from whence we came but that may or may not be oblivion. All you can be certain of is you are not aware of any prior consciousness. There are too many philosophical questions regarding sentience for me to be certain of the ultimate fate of the very curious self.