Ethereal Warfare

"Angels and demons have been fighting for millennia. Battle raged in an ethereal realm far from earth. At one point the demons realised their numbers were dwindling and consequently, they were losing. Although many demons had been possessing humans for years, it wasn't until it began happening in masses that the angels stepped in. Once they did, they realised the demons were possessing humans to not only to raise their numbers, but to attack guardian angels. Bringing the war to earth threatened the existence of mankind. Something had to be done. If demons were bringing humans into the war, angels could as well."