Lots of things were mindblowing in many aspects: Evolution, some aspects of history, Literature, Political Science, Global Warming/climate change science (we believed Christians are called to be stewards of the earth but not in climate science), the earth doesn't have 4 corners, Genetics, probability (gambling is a sin), modernism in art , computers.
With evolution in particular: Evolution was part of this evil mythos I had heard about all my life. At age 12 I was questioning between YEC and Gap Creationism. During this time period I also was allowed to go to lectures at the library and this is how I first ran into the REAL concepts of evolution.
There was a speaker there for adults and his real topic lost me because I knew nothing of evolution or genetics really. I noticed the slides were different then my apologetics books. After the lecture I came up and asked about them so I could form a good rebuttal in the future and 'help' the evolutionist believers if it ever was needed. Seeing how confused I was they very kindly tried to start at the a starting point more appropriate for a young teenager that hadn't heard much about evolution.
For some reason as they talked he absolutely TERRIFIED me. I just had this awful feeling like I was doing something wrong. I felt very guilty for even being there, for asking, for not knowing what to say. I think they knew something was wrong because they asked me if I was alright. I didn't feel alright. I didn't feel alright on the way home either.
Of course I told my parents about my confusion and asked why I would be feeling this way. They told me it was because I knew in my heart it was a lie and it was not the time for me to be exposed to such dangerous propaganda. I was too young to be strong enough obviously. I felt very weak then and went into a very deep prayer regiment to ask for forgiveness and to be protected. I worked very hard to put it out of my mind and began earnestly reading apologetic books in order to be better prepared in the future. I hated feeling weak.
It took YEARS for me to accept evolution. It wore down bit by bit as I grew more independent. For a while I was the most fervent of YEC believers. I was desperate to be stronger and a better Christian (between this and other reasons). I worked very hard and would recite verses over and over again till they were fully committed into my heart. I would role play practice with others like me and study all my subjects very hard. I devoured my approved books. I totally believed that my life was a testament to everyone else and that I had to be ready at any time to explain anything to a non believer. Then I would be strong.
However, I couldn't help but question even in the deepest darkest parts of my heart. I am INSANELY curious about the world. I love to solve puzzles. I love to see how things work. I love to track that things are working and analyze why. I was just drawn to science. Chemistry and math at first. I went off to college and instead of doing a job like my family wanted or at a school that was approved I picked a more liberal Christian school with a decent science program. I had read more on evolution but mostly from a Christian standpoint and would explain it away or try to (some things I had to say were based on faith and faith alone)
The school had professors who taught evolution. I was pretty devastated at first and confused. How could these people call themselves Christian? I had an INCREDIBLY patient biology teacher my first 2 years who I also worked for in the lab. We are great friends. Just through osmosis (she didn't push at all) I gradually began to see evolution not as an idea to fight against or feel guilty when I had to concede could make great sense but as something beautiful. A beautiful force in our universe!
With that came the learned ability to begin to question other things. As I talked to more people who were different than me entire worlds began to open up. Some are wonderful, some are scary, and some are just different but no I do not feel guilt or shame or fear for questioning. It took me a LONG time to get over that though. Exposure and kind people just being around in my life. I also do not think I could have gotten over it if I wasn't a naturally curious person.
My parents tell me my curiosity will get me in trouble but it overwhelms me. The universe is filled with too many wonderous things to hide inside, read books, and recite in hopes that you become strong enough to resist the universe.