The very fact that Jesus was casting out the demons by the Spirit of God was proof that the strong man, the devil, was bound and his kingdom plundered; it meant the Kingdom of God had come. Of course, Jesus did talk about binding and loosing to His disciples (Matt.16:19; 18:18) but that meant more about what believers agreed on or agreed against on earth. They were given heavenly authority. But, with regard to the Kingdom, it had already dawned in the Person of Jesus Christ. The triumph of Jesus was prior to the Cross, in this sense; firstly, because the devil had no authority over Jesus (Jn.14:30), and secondly because Christ was eternally the Triumphant One, the Prince of the Heavenly Kingdom (Heb.2:10; Isa.9:6), who was not subject to the devil like other humans were (Heb.2:14,15). The devil did try to get Jesus, but he failed (Luke 4:6-8). On the Cross, Jesus disarmed the principalities that had a say over humankind. It was a triumph not for Himself (which was not needed), but for mankind. Death itself had no authority over Him (like it had over other mortals); therefore, His Sacrifice alone constituted the Perfect Sacrifice (John 10:17-18). He alone could authoritatively state that He was laying down His life as a sacrifice. The sacrifice of animals in the Old Testament were copies and shadows of this ultimate sacrifice. The animals didn't have the eternal spirit and eternal life, and so they could not procure eternal atonement; secondly, their sacrifice was not voluntary but inflicted and so not "real" in the sense of "sacrifice". But, there was one qualification that they had: the animals were not guilty of Adamic sin; but, neither could they be for they are not moral creatures. Therefore, the sacrifice of animals was a mere shadow (Heb.10:1,4). The coming of Christ dispelled that old system (Heb.10:9,10), and after His sacrifice there remains need for no other sacrifice. By His Body, we are sanctified and perfected forever (Heb.10:10,14).
So, the devil had no authority over Christ and he lost all authority over humanity when Christ prevailed for humanity on the Cross. Therefore, we battle from the place of victory, not for victory.
But, there is a second implication of the metaphor "binding the strong man". The Bible warns Christians to not be careless in their walk on earth; because the devil still prowls about like a roaring lion seeking whom he may devour (1Pet.5:8). And, so we are called to be sober and vigilant. Jesus told His disciples to watch and pray lest they fall into temptation (Matt.26:41). Remember, the thief comes to steal, to kill, and to destroy (John 10:10). So, be vigilant.
1. Be Vigilant Against Pride (1Tim.3:6). Many a man of God has fallen prey to the wiles of the devil when he allowed to be bound with the cords of pride. Submit to God in humility and resist the devil and he will flee from you (James 4:7,8).
2. Be Vigilant Against Lust (John 8:44; Judges 16:18,19; 2Tim.2:22). The lure of worldly lusts can paralyze a child of God. Do not forget that Samson fell because of Delilah and Judas betrayed the Lord of 30 pieces of silver. Lust plunders a child of God.
3. Be Vigilant Against Anger (Eph.4:26,27). Anger can lead to sin and give a foothold for the devil. So, refrain from carnal anger.
4. Be Vigilant Against Envy and Jealousy. Remember that when Saul gave place to envy against David in his life, the Spirit of God left him and an evil spirit began to oppress him (1Sam.16:14).
The above are only examples of places we must be vigilant about. The Bible tells us to hold our ground; not give even a centimeter of earth to the devil at any cost. Certainly, the children of light are not ignorant of the wiles of the devil. (Eph.6:11,13; 2Cor.2:11). Instead of focusing on binding the devil, the Christian must focus on holding his ground and live by the truth that the Kingdom of God has come upon us and the devil and his forces have been routed out.