19 For it pleased the Father that in Him all the fullness should dwell,
20 and by Him to reconcile all things to Himself, by Him, whether things on earth or things in heaven, having made peace through the blood of His cross.
The word reconcile means to bring back to a former state of harmony. The word peace means to establish harmony. If you have ever heard a group of singers you can always tell when someone is singing out of harmony with the rest of the group. But when they sing together in harmony it not only sounds beautiful, you don’t notice individual singers for they sound as one.
So it is when we get born again. Because of the sin nature of our old spirit man we were out of harmony with God. But once we get born again we become one spirit with the Lord. This harmony with God is what makes us so powerful in the earth. The devil wants to keep us blind to the fact that we are one with God. If he can do this he knows he can take advantage of our life through deception.
When a believer realizes they are in complete harmony with God they can go through life victorious for God will never be defeated and neither will the child of God who knows they are one with Him. No weapon formed against a child of God that knows who they are in Christ will prosper, because they are one spirit with the Lord.