How to be rational about rationality

Some things that stick out for me:

In other words, you do not need science to survive (we’ve done it for several hundred million years) , but you need to survive to do science.

Humanity not going extinct is a very low bar! The survival of a species is compatible with very high mortality rate, as long as enough children are born to make up for it. Severe wars and plagues, or even entire nations being wiped off the map, are compatible with species survival.

You shouldn't feel at all comfortable that you are descended from a long line of survivors, any more than you should feel like it's inevitable that you have kids just because all your ancestors did. Their experiences aren't yours. You can die from some combination of stupidity and bad luck, and the evolution of the species will continue just fine.

The rationality of an action can only be judged by evolutionary considerations

This is vague. Evolution of what? An idea? A culture? The species?

It is therefore my opinion that religion is here to enforce tail risk management across generations, as its binary and unconditional rules are easy to teach and enforce.

There may be some truth to this but I think it ignores the evolution and epidemiology of memes, which means that there are a lot of possibilities. Yes, evolution applies to memes but survival and reproduction are primarily about spreading the meme. You can think of a meme like a virus: some viruses are harmless or even beneficial, but fitness for a virus isn't the same as fitness for the host.

Seen from an evolutionary perspective, a meme to spread a religion isn't so different from a cut-and-paste text virus on Facebook promising you benefits if you copy it. The timescale is different, it is true.

People debate whether the invention of agriculture was actually better for the people of that time than hunter-gathering; there's interesting evidence suggesting that it was worse for them. Similarly it's not necessarily clear which attributes of various religions are actually helpful to the believers, versus helping to spread the religion, or just being random. This isn't something that can be settled by general-purpose arguments; it all depends on the specifics.

One thing that seems generally true, though, is that bigger, more coherent groups have advantages over smaller ones. Maybe any belief will do, as long as it helps the group stick together?

There is a difference between beliefs that are decorative and a different sort of beliefs, those that map to action.

Yes, and it may be more complicated. You might be interested in Simulacra Levels and their Interactions which describes four levels of belief, with only the first one being concerned about actual truth.

The fact to consider is not that these beliefs have survived a long time –the Catholic church is an administration that is close to twenty-four centuries old (it is largely the continuation of the Roman Republic). The fact is not that . It is that people who have religion –a certain religion — have survived.

Of course, the people didn't survive. Also, you can't necessarily say that the people who now believe a religion are descendants of people who used to believe the religion, since religions often gain new converts. The only thing we can say is that the tradition survived. Or at least, certain parts of the tradition. (It's not like Latin mass is a thing for most Catholics.)

And sometimes, institutions evolve to be the opposite of what they once were. At least for some beliefs, Republicans and Democrats have switched sides.

Also, it is to the survival advantage of certain memes (but not necessarily us) to have a belief that we should follow the same traditions as our ancestors. This is true whether the meme is all that old or not, as long as we think it's old. Often, there is a fake history behind traditions claiming that they haven't changed for a long time, when actually they are new.

Anyway, if you're interested in rationality, I'm a fan of the somewhat nonstandard definitions of rationality and reasonableness used in David Chapman's unfinished book, In the Cells of the Eggplant.