You get religious groups who think the most important thing God wants us to do is to study to find the correct calendar (God’s True Calendar) and then observe it meticulously.
Calendar cults. That’s what they are.
Somehow I ended up in a Facebook group with some of these people. I decided to play a prank. I’d pretend to love the calendar, and I’d go just a little bit further than they usually did in praising it. This is what happened: