In Noah's day, some angels rebelled and left heaven to live on earth as humans. Why? The Bible says that they wanted to have wives. (Read Genesis 6:2.) But angels were not supposed to do that. (Jude 6) Like those rebellious angels, most people at that time became corrupt and violent. Jehovah destroyed the wicked people with a flood that inundated the entire earth. (Genesis 7:17, 23) But he saved his faithful servants. To survive the Flood, the rebellious angels returned to heaven. The Bible calls these wicked angels "demons. They decided to join Satan's rebellion, and he became their ruler.