3 Steps to Heaven
First you make up a god but because god is 100% good you make up more 'evil' spirits.
Secondly you make the evil sprit responsible for all ills inflicted on mankind.
Then you make up bullshit rituals to fight these made up evil spirits...
Profit.
If ghosts and spirits existed they would be a form of intelligent life. The discoverer of such a thing would win a Nobel prize and be front page news globally. It's the 21st century, can we stop the bullshit already?