May it never be! How shall we who died to sin still live in it?Romans 6:2(NASB)
Just as the work of the Cross provides salvation when we believe it to be true, the work of the Cross also provides victory over the old sin nature when it is believed. We need to understand that the sin nature remains with us until our life on earth is ended - but the blood of Christ has given us victory over the functioning power of the sin nature within our life.
Before rebirth, we are connected to our sin nature much in the same way that a plug on a lamp is connected to an electric socket. When the lamp is plugged into the electric socket, the electricity passes into the lamp to light-up the bulb, but when the lamp is unplugged the electricity has no power to illuminate up the light-bulb. The unsaved sinner is permanently 'plugged into' the old sin nature, which is the only power behind the functioning of the life of every unbeliever.
At rebirth, Christ's work on the Cross permanently severed the power that flowed from the old sin nature into the life of the new believer. The electricity (which represents the old-sin nature), is still there, and the lamp (which represents the believer), is still there, but the connection between the old sin nature and the believer has been severed - forever.
However, the old sin nature is still there, and the believer has the free-will to plug himself back under the power of the old sin nature which causes our thoughts and actions to be influenced by the world, the flesh, and the devil, instead of the new life in Christ.
The power working in a believer either comes from the old sin nature or the new life in Christ. But when Christ died, He not only died FOR sin, paying the price of sin (the death penalty), but He died UNTO sin, providing victory over the dominating sin nature and permanently severing us from the power it has over us. When Christ died unto sin, we died with Him. We died unto sin. No wonder Paul said, "How can we who died as far as sin is concerned go on living in it... How shall we who died to sin still live in it?"
Thank you, Father, that Christ not only died for my sins so that my sins are forgiven, but He died unto sin so that the old sin nature does not have power over me, as I trust my life into His hands. In Jesus' name, AMEN.