Permeating the physical world, there is a spirit world we cannot see and can only barely understand; not only the Holy Spirit, but angels, Devil and demons.
This mysterious realm is most discernible to people who open themselves to spirit influences and powers. Generally, modern Western culture is cerebral and chooses not to acknowledge spirits except in jest.
Christians need not be much concerned about it, except to recognize that the spirit world is very real and can have considerable power over individual lives.
Fortunately, salvation, explained in God's character, takes care of it all for us. When we accept Jesus as Savior, we also get the Holy Spirit. To the extent we yield to the Holy Spirit, he (God within us) drives away evil powers that want to corrupt our lives. We don’t have to think about the spirit world. We just yield to God