Even though God’s eternal decree was declared against Satan almost 2,000 years ago, spiritual warfare between Satan’s kingdom and the Lord’s kingdom continues. Satan has been sentenced, but he has not yet been fully punished or even curtailed from roaming the Earth. The verdict of banishment has been given, but its fulfillment  awaits the final judgment at the end of the age. Then Satan and his assistants will be cast into the lake of fire.  

In the meantime, Satan pretends to exercise authority as the prince of this world, even though this authority has been taken from him. He only succeeds when through our ignorance we become prey to his deceit, lying, and other malicious schemes.  

God has a purpose in allowing the enemy to roam the Earth and war against the children of God. God is developing us as sons as we learn to overcome Satan by using the weapons and provisions God has given to us in Christ. Our character is developed as we learn how to resist Satan in our own lives and how to deliver others from his snares. (See Ephesians 6:10-18; Revelation 12:11; Matthew 4:1-11; I John 3:8; 1 Peter 5:8, 9.)  

 It is only because Satan has already been judged by God that our resisting him in union with Christ is effective.  

Submit yourselves therefore to God. Resist the devil, and he will flee from you (James 4:7). 

 To execute upon them the judgment written: this honour have all his saints. Praise ye the LORD (Psalm 149:9).