God is a spirit. No one has ever seen Him, hence no one can describe Him. His son was seen in a human body. The Holy Spirit only hovers around and has never been seen or touched. The traditional African society had numerous versions of this God until the Missionaries came and changed the story. Their beliefs worked for them well.
On the other side the devil apparently works to outdo God who is believed to be all-powerful. The ancient societies had this side of the story as well, where they believed there were spirits who worked on tormenting people and destroying the good.
Witchcraft appears to have both sides. The good and the bad. Apparently they can make a good situation bad, and a bad one good. It still works for those who believe.
There are others who believe in intelligence. I consider this particular group limited because they only believe in what they can prove to exist. They do not pray and possibly rarely seek spiritual intervention in their matters. This version of their life works for them as well.
Now consider the current wave of miracle churches, miracle pastors, evangelists and prophets. They create their own versions of faith and prayer. From telling their followers to come naked in church, to suckling women breasts, to not believing in conventional medicine and to extremes of trying to swallow live snakes! This kind of thing still works for them. In fact they are more thriving than their more ancient counterparts.
When it comes to matters of faith and spirits, it is more of coming to a consensus and not what spirit is stronger than the other. I tend to think that the strength depends largely on the acceptability of the spirit in question. If one can market their spirit like the Christians did, it can work perfectly for them.
I am convinced there are other less publicized spiritual practices around the globe. If they get a worthy backing, probably from a popular world celebrity, they would go viral. So I think.