If a card were to be place in a book, everything the book was subjected to would be experienced by the card. Leave the book in the rain, and the card gets wet. Throw the book in a fire, and the card burns. Nail the book to a tree, and the card is pierced. Take note of these verses:

Romans 6

Verse 2: “How shall we who died to sin still live in it?”

Verse 3: “Or do you not know that all of us who have been baptized into Christ Jesus have been baptized into His death?”

Verse 4: “Therefore we have been buried with Him through baptism into death.”

Verse 6: “knowing this, that our old self was crucified with Him.”

You were in Jesus as he walked up Calvary. You were in Him when He was nailed to the cross. Like that card in the book, you were crucified in Him. This was a physical phenomenon for Jesus; it was a spiritual phenomenon for you. This was the first step as He was preparing to re-create you as a clean vessel so He could cohabit your spirit with you once you became a saint!

D. Martin Lloyd-Jones left his career as a physician and became one of the world's most well respected theologians. He wrote an entire book about chapter 6 of Romans. Look what he says about our crucifixion in Christ:

The old man is the man I was in Adam; that is the man that has died once and forever. This is, to me, one of the most comforting and assuring and glorious aspects of our faith. We are never called on to crucify our old man. Why? Because it has already happened—the old man was crucified with Christ on the cross. Not to realize this is to allow the devil to fool you and to delude you. What you and I are called upon to do is to cease to live as if we were still in Adam. Understand that the “old man” is no there. The only way to stop living as if he were still there is to realize that is not there. If you are a Christian, the man you used to be has gone out of existence; he has no reality at all; you are in Christ. If we but saw this as we should, we would really begin to live as Christians. We would all hold up our heads, we would defy sin and Satan, we would rejoice in Christ as we ought. [Romans, Exposition of Chapter 6. Zondervan. Page 65]

Had God not fixed it so you would die in Christ, when you were reborn as a Christian, you would be spiritual conjoined twins, one evil, one good, who constantly fought for the upper hand—a spiritual schizophrenic, a “house divided against itself.”

Christians in the first three quarters of the twentieth century were taught that we have two spirit natures, one good and one evil. The church that continues to believe and teach this untruth about our spiritual identity will be a defeated group of warriors who sound pretty brave as they praise the Lord in the assembly, but get picked off by snipers as soon as they hit the parking lot.

Your new nature replaced your old nature. Your old nature lives no more! You are not a house divided. You are a house undivided. That is who you literally are. It's your true identity.