ya know, thinking about it, all humans have 3 brains. our root brain, the brain-stem, actually acts in a reptilian/primordial manner. it is not til the age of 7 or so that our second brain, which forks either to the amygdala (fight or flight) or the thalamus (lymbic system), begins to develop. the amygdala is already pre-developed and is where our sense of survival stems from. It is also constantly watching and making sure everything in your immediate surroundings is ok. it kicks in when there is any potential danger, forcing you to act before you can think. The thalamus is where most humans function. This is where we get our sense of family, friends, and society. what all you non traumatized people experience normally, traumatized people have no sense of.
Having grown up with PTSD since the age of 6, i can assure you, without the lymbic system, humans are downright evil. lots of love and grace from everyone in my life kept me away from doing any harm, but I can easily see how someone who wasn't as fortunate as me could easily turn against God.
What I typed is from personal experience. This is the conclusion I came to after seeing many different doctors for so many years (33 actually) and them teaching me about PTSD along the way. the following link and attached pic are references to a book I found many years after many trauma. Everything in the first half is accurate. I came to the same conclusions as this doctor. unfortunately I had to experience it to learn it.
https://doctorlib.info/travma/body-keeps-score/4.html