Hi there!
I share the interest of the OP, largely because the more critical thinking I learnt and applied, the less I believed in the religion I'd been brought up in. It's not much use trying to explain exactly where I am right now, because that keeps changing, hence my blog, but since I got over the "4 hump" in the middle of Dawkins' scale, I've been coasting down the hill ever closer to 7 without no real effort.
Speaking for myself, and not intending my experience to be taken as normative in any way, I found that religion was very difficult to let go of. There are so many cognitive biases and tricks that can be deployed to create or maintain belief, and once you're in, you pretty much do it yourself, because a threat to your beliefs becomes a threat to your identity, self-worth and relationships with friends and family. Looking back, I think the fatal blow for me was dealt 13 or 14 years before I left the church, but I did everything I could (generally not consciously) to battle that, because I didn't want it to be untrue, and in Christian circles, doubt was generally treated with pity or even scorn. As Feynman said, "The first principle is that you must not fool yourself, and you are the easiest person to fool."
Religion is chock-full of clever ways of not answering questions in "deep" ways, which also helps to convince you that you're clever and anyone asking difficult questions doesn't really understand - look at how often Dawkins is vilified or described as ignorant because he asks those questions. If you accept the reasoning, it becomes really quite easy to defend those beliefs. Take transubstantiation, for example - objections can be deflected by claims that only the substance changes, not the material, or in the last resort that God wouldn't allow himself to be tested. It's easy to feel that your beliefs make sense if you can dismiss arguments like this, but in reality the offence against critical thinking is the "arguments" you cling to like a liferaft because they help you to win the argument. It's argumentum ad Sagan's Dragon.
The best way of changing your beliefs is not to know the "right" answer, and to think about it for yourself. I think my beliefs were shaken when I was asked why God doesn't heal amputees, but completely holed below the waterline when I discovered how laughably weak the historical evidence for Jesus is, and how long it was before any gospel accounts were circulating. Around that time, I was humiliatingly taken in by the blatantly obvious
NASA/Joshua hoax. I was so embarrassed at my gullibility that I think that incident was a huge factor in me taking an interest in critical thinking and eventually deconverting.
Despite that, I tried all sorts of things to hold onto what there was of my faith, and for a while, I was even keener than before. I tried focusing on how the church had come into being - it clearly did, so something huge must have happened to convince them that it was true. When that started to crumble, I went in for experiential Charismatic beliefs, trying to find another basis for my existing beliefs. I tried on different understandings or interpretations, adopting the label Christian Agnostic (which was more or less code for "I'd like it to be true, but if I'm honest I don't think it is") and finally a sort of weak culturally Christian form of Deism. Each time, I was eventually forced to concede and change my belief. Even then, it took a proper reason (same-sex marriage) to force me into leaving the church, rather than just sticking around and not causing a fuss.
