'Patterns in Prehistory' class where we learned about pre-history civilizations. Saw that there is a book, 'Patterns in Prehistory: Humankind's First Three Million Years', which covers the topics were covered in that class. Initially, I was like 'why should I learn pre-history?' and I postponed it until the last semester of my undergrad. Learning different civilizations and their religious beliefs made me start questioning my religious belief.

And an NPR podcast, "Is Believing In God Evolutionarily Advantageous?", which explains why human are religious.

Those two changed my religious belief, so I can say that they changed my life.