Religion and Spiritualism

However many holy words you read, however many you speak, what good will they do you if you do not act upon them?

— Buddha

Religion and faith are powerful forces in the world - even more in settings where the gods they worship are real and present. Here's some resources on religions and faith, cults and schemes, gods and devils.
As is so often the case with faith, what people believe is more important (and changes your setting) more than what is actually real.

Palo Mayombe

Palo Mayombe - a little known Carribean faith with deep roots and connections to the slave trade. That alone makes it a topic to approach with some care, but it is an interesting and little explored belief in most fiction (or any media, really). It involves ritual cauldrons, called an Nganga, spirits of the dead and of nature, sacrifice, and more.
https://www.palomayombe.org/
Go here to have a deeper dive into Palo Mayombe. Most of the content can be found in the Blog part of the site, like this:
https://www.palomayombe.org/the-palo-mayombe-the-ever-powerful-force-of-black-magic/

Podcast: Cults

A podcast dedicated to exploring cults.
Some good episodes.

The Strange World of Breatharianism