back in your christian days.
The holy spirit has nothing to do with ghosts or specters, it has to do with the human enlightenment and the belief, not about god walking the in non corporeal form. It's basic Christianity 101 dear girl you are the one that needs to read. The holy trinity is more a mantra to remember what is important about Christianity and remember the teachings that's it's significance.
To remember "The Father" God creator, "The Son" Jesus - who gave his life so that Christians could live and "The Holy Spirit" the sense within that ties them to the first two the reason they go to church every Sunday.
It is you who needs to go back and read....

"Your born, You Live, You Die, given this premise, one can conclude since we have no control over when we are born and when we die, the only thing that matters to us should be how we live, simple really?" Mis-Cat to her philosophy Lecturer.