This also illustrates the bad research that goes into this sort of thing. There are no deep roots of 'TESCREAL' (which doesn't exist to begin with) in Russian Cosmism, because there are no roots of any of those ingredients separately in Russian Cosmism.

Stross just made that up, as pure post hoc ergo propter hoc. There are no sources, and he got it from Hannu: https://gwern.net/review/quantum-thief#fn2 Stross has chosen to never revisit the topic to try to substantiate his suggestion.

This quote winds up being rather exemplary: for example, that one parenthetical description manages to make at least 3 errors: 1. Fyodorov was born in 1823, so he obviously could not have invented anything in the '18th century' (ie. 1700s); 2. Cosmism included many things, not just the 'Great Common Task', and the Great Common Task itself went far beyond reviving ancestors, including many overall more important things like colonizing the entire universe or conquering death; 3. and further, the revival part was not about computer simulation at all (that's Hannu's _Quantum Thief_ fictional version of the idea that he came up with for his Sobornosts!) but reviving them physically, in the body, possibly using cloning - and was no more about "inside of a simulation" than Jesus reviving the dead was.

You're right that Hannu made great use of Cosmism as world-building in the Quantum Thief trilogy which I highly recommend (see my review above) - but that could only work because the ideas of Cosmism are so novel & exotic, and not part of Western transhumanism. If they really were as foundational as Stross claims, the 'taproot' of Western ideas, they would make about as exciting fictional worldbuilding as suggesting that you have some sort of 'laws' for AIs, starting with 'An AI may not injure a human being or, through inaction, allow a human being to come to harm."...