The Power to Live a Holy Life
John 12:31 "Now is the judgment of this world: now shall the prince of this world be cast out."
The only reason Satan ever had any right to become a prince or rule over us was because we yielded ourselves to him through sin (Romans 6:16). Since Jesus "bore our sins in His own body on the tree" (1 Peter 2:24), Satan no longer has power or authority over those who accept Jesus' gift of salvation. Satan has been "cast out" -- stripped of any power he had. Now he can only deceive, and if we fall for his lies, we stop God's blessings from flowing in our lives.
The reason why a believer must live a holy life, is to avoid Satan's bondage. When we obey sin, we yield ourselves to Satan, the author of that sin. Yielding to sin is yielding to a person, Satan. God doesn't impute the sin to us but the devil does. Our actions either release the power of Satan or the power of God in us.
Although God is not imputing our sins unto us, we cannot afford the luxury of sin because it allows Satan to have access to us. When a Christian does sin and gives the devil an opportunity to produce death in his life, the way to stop him is to confess the sin. God is faithful and just to take the forgiveness that is already present in our born-again spirit and release it in our flesh, thereby removing Satan and his strongholds.
A person who abandons himself to sin is actually becoming a slave to the devil while a person who obeys righteousness is yielding himself to the Lord. This is why a Christian should live a holy life.