Ephesians3:10 (KJV) To the intent that now unto the principalities and powers in heavenly places might be known by [through] the church the manifold wisdom of God.
God doesn’t come down and tell the devil how smart He is. He shows him how smart He is through us, the church. God had a secret from the foundation of the world before all the ages began. After the fall of Lucifer, when evil was found in heaven and earth, God had a plan which was hidden in Himself for a day to come when every believer would be able to show on the earth “the manifold wisdom of God.”
When Jesus rose from the dead, He gave all authority back to the church in His name. When a believer uses the name of Jesus, all hell comes to a halt. God is glorified, and the devil is humiliated. God smiles at Satan because we show forth His wisdom. We are inferior creatures to angels (Psalm 8:5; Hebrews 2:7) of whom Satan was a leader. We may be inferior by creation, but through the new birth, we are superior by position. What is so humiliating to Satan is to be stopped through the authority in an inferior creature—man.
You cannot stop Satan in your own name, but you can in the name of Jesus. In the name of Jesus, you can cast out devils, speak with new tongues, and lay hands on the sick, and see them recover. (See Mark 16:17-18.) That is the purpose of the mystery which was hidden in the heart of God. Can you now see why it was so important for Paul to get this truth across to the believers of his day and ours?