I was born and raised in it and bought into it for a long time. I think what finally began to make me stop and think was when they would admit that obedience was more important than being right, using examples of people who were removed as apostates, only for the organization to adopt their views later on. And they would say it directly- the important thing was obeying the organization, more than being right about Biblical interpretation. Even though I told myself that this was right and okay, there was apparently some level of my brain that could not make that square peg fit into a logical round hole.
Even so, I think I fought it until I finally came to the realization that I didn't believe in God. At that point, with the presupposition removed and giving myself the permission to think freely, lots of what they taught fell apart. It was at that point that I started to read stuff like CoC and learned that they'd been hiding all of their dirty laundry from us, and there was an astounding amount of it.