The Greek verb diaballō (from dia = across/against + ballō = to throw) means 'to throw across,' 'to slander,' or 'to accuse maliciously.' It is the verbal root from which diabolos (devil, 'the slanderer') derives — making this word the etymological foundation for understanding Satan's primary activity.
Diaballō appears only once in the New Testament (Luke 16:1), but its significance is enormous as the verbal root of diabolos (G1228, 'Devil'). The Devil is literally 'the Accuser' — the one who throws accusations across, who slanders God to humanity and humanity before God. Understanding diaballō reveals that Satan's primary weapon is accusation and false accusation. This is why Revelation 12:10 describes his defeat: 'the accuser of our brothers has been thrown down.' The cross silences the ultimate diaballō.