Was just thinking about how militant misotheists seek to kill Wayfarers in order to starve the Uncreated Light of worshipers in revenge for cursing the yinrih with sapience. There's a potential contradiction in misotheist doctrine here. The noosphere is only effected by the emotions and beliefs of sophonts and if, according to this doctrine, the Uncreated LIght only exists because Wayfarers believe it does, then it can't have caused the Kindling because there were no Wayfarers to believe in it.
Misotheists may offer different apologias for this doctrine:
1. The Light is the result of the beliefs of some or all monotheists in the universe, not just the Bright Way, and came into being when monotheism was first conceived by some ancient race of star folk.
2. The Noosphere is not bound by the causality of realspace, and once the Light came into being it had always existed. (IIRC this is the way the Immaterium works in WH40K).
3. Similar to number 1, but humanity is blamed specifically. According to this view, because there's no written record for most of modern humanity's existence, some human tribe professing monotheism that predate the yinrih's kindling brought the Light into existence.
Militants likely argue for number 2, since it would make their goal more achievable compared to killing all monotheists in the universe. I should hasten to add that not all misotheists are militant. Indeed, because of their tendency to isolate themselves and invent constructed mythologies, many, misotheists don't hate the gods they believe exist and thus aren't technically misotheists even though the group they came from are.
On a similar note, I haven't developed the atheist faction of atavism much. The ideas I do have for them are a lot bleaker than I want to go with the lonely galaxy, like self lobotomy or suicide cults. Indeed, why they don't merely kill themselves if sapient existence is so miserable is a question I have yet to answer. Perhaps they believe existence in blissful ignorance as a non rational animal is preferable to oblivion.
One idea that I think may have legs is “reverse eugenics” (dysgenics?) where they try to breed sapience out of their own population.