I used to be a very conservative religious person. I had a whole package of beliefs that were ingrained into me from birth, and I grew into them and claimed them as my own. I thought that homosexuality was very damaging to society. I thought that human caused climate change was either fake or that there was nothing to worry about even if it were true. I did not believe that humans evolved, or at least I was somewhat conflicted about that. I thought that creationism belonged in schools. At one point in my early twenties I even listened to Rush Limbaugh and agreed with him (I cringe every time I remember that). I knew so many things, and I was happy to know them.
I also liked to think analytically and enjoyed the intellectual stimulation I got from certain online forums (this one included). I liked how people would trade counterarguments and keep each other honest by pointing out bad thinking or logical fallacies. When someone would argue against something I believed in, I would argue back. From their perspective, my mind was not being changed and they were wasting their time, but from my perspective, the things they would call me out on stuck with me. I tried to avoid falling into logical fallacies and bad arguments because I knew I'd be called out on them. This restricted the ways I had to justify my beliefs, so that made it challenging. Then at church I noticed that nobody was being held to these standards at all, and fallacious reasoning was being let fly freely and constantly. I experienced a lot of cognitive dissonance during that point in my life which ultimately led to deeper investigation and study. I give a lot of credit to honest online debaters who pushed back on my ideas and kept me honest about the substance of my arguments.
Care to give any examples and the reasons for your first position and subsequent change?