Here is an excerpt from Revelation, Chapter 12:
“And another sign appeared in heaven: behold, a great red dragon, with seven heads and ten horns, and on his heads seven diadems. His tail swept down a third of the stars of heaven and cast them to the earth…Now war arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back, but he was defeated, and there was no longer any place for them in heaven. And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole world — he was thrown down to the earth, and his angels were thrown down with him.”