Out group punishments are there to control the thought and action of the in group.
Threats being as good as actual action.

belief in heaven and hell is the slippery slope into a miserable life...

Never heard that hymn before but at least it portrays some of the beliefs of some of the believers.

I think understanding that all religions are man made to try to explain the things we can't figure out. Before scientific methods were formed, beliefs were what people had and when it comes right down to it, all they still have if they are in an area that doesn't have a decent school system with a fair science department. It seems to be bred into us, woven into our social interactions and teachings no matter what society you look into. Every one of them have culturally tailored religious ideas and beliefs.

Some religions just developed an elitist streak I think, Baptists apparently being one branch. It doesn't take much poking around though to see they are not alone. There are a few that are more inclusive though in their afterlife ideas that worry more about behavior towards others as a marker than simply belief. I find those more tolerable as they generally lead with an honest good will. To me those are acceptable. They don't really care what others believe as long as they treat others decently. I'll take that over that elitist attitude as it often comes with a lot of aggravation and asshattery that I just don't care to deal with.