I'm not sure what you mean by 'deflationary'. Could you please qualify.

Evolutionary biology was perhaps originally about the origin of species, hence Darwin's title. It seems to have moved on into other areas, for example Diamond's attempt to explain the origins of religion.

Indeed I am talking about naturalistic philosophy in general, which is what Darwinian evolutionary theory is based upon.

Your suspicion about the early experience of gods was nothing less than what I would expect from someone who doesn't believe in them. I suspect that the handling of entheogens was actually highly sophisticated, as in the Mystery traditions, not naïve, leading to direct experiences of the spiritual realms. Such experiences may have been so powerful that there was no possibility of, or need for, skepticism.

I don't think that the feeling of belonging to a greater whole is medieval. If we've lost it, then it's something that we need to return to, and modern science is helping us (quantum physics, the interconnectedness of all things). The revolutions of modern liberalism you describe have taken us too far in the other direction, resulting in so many of the world's problems. We fail, for example, to understand that we are part of the superorganism of the Earth (James Lovelock's Gaia hypothesis).

I agree with you completely that we need a new mythology, although I don't associate that with fictions. I'm closer to the thinking of Ananda Coomaraswamy: “Myth embodies the nearest approach to absolute truth that can be stated in words”. There is still profound and timeless truth in the ancient myths, if they are interpreted correctly (Joseph Campbell, Carl Jung). And there is indeed sacred in the (apparently) profane.

I did write a long series some time ago about the need for a new mythology. If interested, see under Mythology on this page of my website.

I've also just published part 2 of Religion and Evolutionary Biology:

https://medium.com/@graham.pemberton/religion-and-evolutionary-biology-part-2-d256c2d53a63