A couple thoughts here...

Palmer's handling of the different groups in Terra Ignota takes both sides, in every case. The case for why people join the imperial group has to be made, and made honestly. But problems with that approach are also pretty clear, and well explored: at the very least, elites get weird if they aren't responsive to the people, and the elites in Terra Ignota get very, very weird. I think she takes a bit more time setting up the positive case for the imperials exactly because it's pretty alien to us. Or, at least it was before our current global swing towards authoritarianism.

Europeans were also once pretty obsessed with religion, as you might recall. They may be less so now, but who's to say the pendulum won't swing? This is one of the things I loved about the series -- the future or build is very different because the pendulum has swung in ways that aren't obvious to us, from our modern perspective. Just as the people of Florence would find some of our obsessions pretty strange and unexpected.

good thoughts. Thanks for sharing :)