AS MANKIND multiplied, sin and wickedness spread rapidly in the earth. A lone prophet named Enoch warned that God would one day destroy the ungodly. Still, evil prevailed and even worsened. Some angels rebelled against Jehovah by leaving their assigned places in heaven, assuming human form on earth, and greedily taking women as wives. Those unnatural unions produced hybrid offspring​—giant bullies called Nephilim who intensified the world’s violence and bloodshed. God was deeply hurt to see his earthly creation being ruined.

After Enoch’s death, one man stood out in that wicked world. His name was Noah. He and his family tried to do what was right in God’s eyes. When God decided to destroy the wicked people of that world, he wanted to protect Noah and earth’s animal creation. So God told him to build an ark​—a huge rectangular vessel. In it, Noah and his family would be preserved alive, along with numerous animal species, through a coming global flood. Noah obeyed God. During the decades that Noah spent building that ark, he was also “a preacher of righteousness.” (2 Peter 2:5) He warned people about the coming Flood, but they ignored him. The time came for Noah and his family to enter the ark with the animals. God shut the door of the ark behind them. The rain fell.

The rain came down in torrents for 40 days and 40 nights until the whole earth was submerged. The wicked were gone. Months later, as the waters receded, the ark came to rest on a mountain. By the time the ark’s passengers could emerge safely, they had spent a full year aboard. In thanksgiving, Noah presented an offering to Jehovah. God responded by assuring Noah and his family that He would never again bring a flood to wipe out all life on the surface of the earth. Jehovah provided the rainbow as a visible guarantee, a reminder of this comforting promise.

After the Flood, God also gave mankind some new commands. He granted them permission to eat the meat of animals. However, he prohibited the eating of blood. He also commanded Noah’s descendants to spread abroad in the earth, but some of them disobeyed. People united under a leader named Nimrod and began to build a great tower in the city of Babel, later called Babylon. Their aim was to defy God’s command about spreading throughout the earth. But God thwarted the rebels by confusing their one language and causing them to speak in various tongues. Unable to communicate, they abandoned the project and scattered.

​—Based on Genesis chapters 6 to 11; Jude 14, 15.