Satan Casts Himself Out Thru the Cross. Mark 3:20-30.
Satan's house is a house divided and cannot stand. It has fallen, is falling and will finally fall thru the Cross of Christ.
In the above cited verses Jesus discloses the mystery of how God always defeats and casts out evil without firing a shot or destroying anyone with direct violence. God destroys only thru the cross always. Heb 2:14.
At the cross, Satan's house is divided against itself and casts itself out. Ps 7:15-16; 9:15-16. John 12:31 was spoken by the Lord on the eve of His cross event. The judgment and casting out which He spoke of was a reference to the cross event. Satan was judged and cast out by his crucifixion of Jesus. Satan, the strong man, was bound at Calvary, in his own house, the world, just as Haman was hung on the gallows he built in his own yard for hanging Mordecai. Esther 7:10; John 12:30-33.
This same same principle of the cross works for all followers of Jesus: take up the cross daily (Luke 9:23-25) for Satan to be cast out of us as well as out of the situation and possibly out of other parties that are involved in the situation.
See also Rev 12:7-12. It is the wrath of the LAMB (the wrath of the CROSS) that causes Satan to be cast out Satan in every and all situations even at the end of time.