How does Satan accuse believers before God?
Satan accuses believers before God by constantly bringing their sins and failures to His attention day and night. As the accuser of the brethren, he points out every time they sin, running to tell God where they have failed, until he is cast down from his access to heaven.
Les explains from Revelation 12:10 that Satan is the accuser of our brethren, who accused them before our God day and night. He had access to the throne room of heaven until Michael and the holy angels fought and defeated him, and he was cast out. Les points out that every time we sin—and we all do—Satan is the first to run and tell God about it, constantly letting the Lord know where we have failed. This accusation continues until Satan's final access to heaven is removed, as described in the war in heaven.
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.
More Questions
How does Satan's accusation of believers show that believers can still sin?
If it were impossible for a believer to sin, Satan would have had nothing to accuse them of; the fact that he keeps accusing believers shows believers can still sin.