I think this might actually be based on a true story. I had my suspicions 3 years ago, when I first started reading this series. The fact that it was arbitrarily set in the late 90s when most manhwas are set in the modern day. The fact that Pyo's narration would occasionally be from his future self (like in that one chapter, around chapter 56 or so when he was still in high school) where he said "little did I realize things were about to get a lot more interesting for me."
I did some googling and there were scandals involving church mega pastors in south korea in the early 2000s. So the timeline adds up, but I just can't pinpoint how this manhwa series lines up with events that actually occurred.