Revelation 12:9-11
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
10 And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.
11 And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.
The Bible teaches that Satan is the great accuser. He stands in the presence of God day and night trying to convince God that we are all worthless and rotten. What do we have to argue against him? If we show our good deeds, Satan could pull out a dozen bad for every good. If we bring up our cheerful demeanor, he could answer by showing every time we’ve lost our temper. The devil has an answer for anything we can say because he’s right about us, we are worthless and rotten. But notice verse 11. When we start bringing up the Blood of Jesus, the Devil doesn’t have an answer. When we offer our testimony, Satan loses his ground. What is the testimony of everyone who has ever overcome Satan? That Jesus Christ is faithful and that His blood can lift us up higher than we could ever fall down.