Matthew 28:18
And Jesus came and spake unto them saying, "All power is given unto Me in heaven and in earth.
This verse is one of the most powerful and meaningful verses in all the Bible for you and me. The word here rendered "power" is more literally translated "authority." Therefore, it would read, "All authority is given to me in Heaven and in earth." Jesus has all authority and all power, there is none higher than Him nor is there any mightier than Him.
When Christ ascended, He transferred His authority to the Church. He is the Head of the Church, and believers make up the Body. Christ's wants His authority to be perpetuated through His Body, which is on the earth. All through Ephesians and elsewhere in the epistles Paul uses the human body as an illustration of the Body of Christ.
Christ is seated at he right hand of the Father, the place of authority, and we are seated with Him. If you know anything about history, you know that to sit at the right hand of the King denotes a position of authority. We died with Christ, and were raised with Him. This is not something that God is going to do in the future; He has already done it.
The resurrection was one of God's greatest acts. (Ephesians 1:18-22) It was opposed by Satan and all his cohorts. They tried to hold Jesus in the grip of death, but God took Him right out from under their noses and they were powerless to stop Him. His forces were confused and defeated by our Lord Jesus Christ, who arose, ascended and is now seated at the right hand of the Father, far above all of them.
We are told in Colossians 2:15 that he spoiled the devil and his powers and made a public spectacle of them. These are the same demonic powers that we face today. But thank God, Jesus has already defeated them and paraded their defeat before Heaven, Hell and earth. If Jesus defeated them, then we did too, because we are seated with Christ in the heavenlies. We have His authority to deal with our enemies.