“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. 10And 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. 11And 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.” Rev. 12:9-11
Satan was overcome in heaven and he can be overcome on earth. Not by all, but by those that have the kingdom of heaven in their heart. Satan cannot overcome where God’s kingdom is.