> Also related to the ending, I‘ve come to realise more and more that most people reason out of belief first and arguments second on a lot of things (maybe most things?)

This is the thesis to the introduction to Jonathan Haidt's The Righteous Mind. Boiling it down, he argues that self-justification is the most fundamental human reaction. We reason after, not before, and our reasoning flows to align with our own justification.

(Luther would be proud.)