Since the days before the Great Flood, angels, called Nephilim, roamed the land and began to breed with humans, destroying the DNA of mankind and infecting the human race with the evil that had infected them from the fall of Lucifer who then hated God so much he brought sin to the earth in the form of a serpent causing Adam and Eve to fall in the garden, allowing generational sin to continue down through the ages. Just as sons and daughters receive an inheritance from their parents, they also receive sin from the parents as well. But why did Lucifer do this?
If we go to the Bible, I think we can find the answer. It began with the creation of the angels, especially the angel Lucifer who is described in the Book of Isaiah 14-12 and Ezekiel 28-13 as being perfect in all his ways until sin was found in him. He was also described as the most beautiful creature God ever made. Diamonds, rubies, and emeralds were his covering. In other words, he made the jewels of the earth look good.
But again, why did he fall? I believe one day, Lucifer took a long look into the mirror and thought to himself; Man, you are one good-looking dude. Any angel that looks this good should be a god himself. And it caused pride to well up inside himself, causing him to sin. Did God know Lucifer would sin? Sure, he did. God is omniscient. There is nothing hidden from him. God also saw the pride well up inside Lucifer, for God is also omnipresent as well. And like the infection the angels brought to the earth, Lucifer infected a third of the angels of heaven, causing war in the third heaven, which is in the sides of the north.
And there was war in heaven and Michael the Archangel along with His angels fought with the Devil and His angels. (Revelation 12:7)
And the devil was kicked unto the earth, taking one-third of the stars, which are also called angels with him., which brings us back to the Great Flood. God saw what the angels had caused by mating with humans. To stop the destruction of man, God sent the flood to destroy the angels' DNA off the earth. Only eight souls were saved to carry on the human race, and to make sure the angels no longer mated with humans, their angelic bodies were taken away, leaving them with a disembodied spirit, to be called by mankind by the term demons.
This stayed the same until the tribulation period when ten of these evil spirits gained their freedom to inhabit human bodies once again. They created a conspiracy to destroy humans using an information chip which every human would have to take if they were to buy or sell anything. Without the chip, you would die. If you took the chip, you were bound for a lake of fire, a place that was made and reserved for the devil and his angels. The Pyramid conspiracy was instituted by these ten with the Antichrist at the top.