Why Certain Parts of the US are Religious and Others Are Not

A while ago I watched a video that pondered that very question. They talked a lot but failed to get to the core of the issue. The core is that different denomination of Christianity is very different from one another. Some are very nice and others not at all. There are many different denominations in contemporary US, but most originated from either puritan or anabaptists.

Puritans and Irreligious Parts of the US

Puritans originated during English Civil war and were official state religion during Oliver Cromwell times. Back then they banned celebration of Christmas and other religious holidays because they thought holidays were distraction from proper faith and are too immodest to be Christians.

They were broadly unpopular with general population. So unpopular that public supported restoration of monarchy in order to get rid of puritans. Afterwards puritans and their practices were banned from England. 

Instead of learning that their denomination is unpopular mess and public hates it, they decided to instead migrate to the modern US and set up Plymouth Bay colony in New England area. 

Puritans thought that their faith will survive in the area controlled by puritans and inhabitant solely by puritans. That was only true for a first few generations. While original settlers were all supportive of radical puritan views, their descendants were not. Eventually puritanism died out.

Nowadays former puritan areas became almost completely irreligious. Memory of puritanism makes people in all areas affected by them completely irreligious. Puritanism is as oppressive and totalitarian as Orwellian Ingsoc. Absolute majority does not want to believe in anything like that.

Despite that puritanism was not completely extinguished. A certain fraction of puritan descendants does tries to resurrect some or all of puritan practices under new guise. Sects such as Jehovah Witnesses are likely inspired by puritanism.

Baptists and Bible Belt

Situation in southern US is completely different, however. Most popular denomination there are Baptists. Baptists are likely originated from European Anabaptists of the Reformation times. Anabapists were called this way because they opposed infant baptism of Catholic Church, insisting that only adults that are capable to understand faith and consent to it should be baptized. This practice is continued by modern Baptists.

European public was not keen on adult baptism because during these times a child could die in infancy, and they wish for them to enter heaven, nonetheless. European rulers too wanted a more controllable religion, such as Lutheranism so Anabaptists too migrated to relative freedom of the colonies. There they eventually became Baptists. 

Unlike strict, ascetic and totalitarian puritans anabaptists were all about unconditional love of God. They even went as far as helping out their enemies who wanted to kill them. Instead of strict rules Baptism has help, charity and love of God. It is them who say that Jesus loves you.

Conclusion

Unlike puritanism, baptism is much nicer and more agreeable religion. It is a religion that can attract and retain people with its kindness, care and support. This is the real reason why there is a bible belt in the south and irreligiousness everywhere else in the US. People who escaped puritanism now want to avoid anything that resembles it even remotely. In contrast people who experienced baptism want to stay with this nice and helpful faith.

Extra

There was another video that claimed that people who see other practice religion are likely to be religious themselves. In response to that I would like to point out to Asch experiment where a person was shown two lines of clearly different length. Before they asked them if the lines are the same length or different, they asked three assistants to all look at the same picture with lines and then state that lines are the same length.

People who claim to be religious after seeing people practice religion are not retaining faith, they merely feel social pressure to conform and claim to believe.