It is not an invention but just an opinion. All creatures including human beings are ruled by different kinds of spirits. God is a mystery even to these spirits. That's why you are able to see atheists even at this miraculous era of God. The people who born in this era cannot realize the existing situation on earth. Their grand parents must explain in detail.
Spirits are separate elements. A human being is not a single spirit. A human being doesn't have a spiritual body. A human being during his/her lifetime is living with many spirits which have joined one by one since birth. They are knowledge, skills, feelings, emotions, interests and everything. Even thoughts are not your own. For example, when you want to take a decision on a subject, one after another the spirits think and you just listen, choose or reject the ideas which they transmit to your mind through your brain in the form of thoughts. Brain is just a media to connect the spirits to your mind. A mind is just a computer's mind. After the destruction of a computer completely you will not get it's mind. The same is the case with the human beings. Soul is nothing but an energy needed for the functionality of a body. It is not a spirit or anything else. All human beings are just robots made of flesh and bones and toys of the spirits for their games.