The old man is gone because of what Christ accomplished on Calvary. We are not sinless, but we do “sin less” because we are no longer dominated and controlled by sin. While sin used to rule, it is now Christ who rules.
5 For if we have been united together in the likeness of His death, certainly we also shall be in the likeness of His resurrection, 6 knowing this, that our old man was crucified with Him, that the body of sin might be done away with, that we should no longer be slaves of sin. 7 For he who has died has been freed from sin. Romans 6:5-7 (NKJV)
Romans 6:6 clearly shows us that true believers become holy in Christ. However, there is confusion because many do not look correctly at the Greek verb tenses in this passage. If they simply read it in English or some other translation it is easy to not see that the all the verb tenses here are past tenses (aorist or perfect). What this means is that every verb tense here that refers to our identification with Christ in His death refers to it being completed in the past. Romans 6:6 translated literally says, “knowing this that our old man was crucified with Him that the body of sin may be made ineffective.” This took place way back when Christ died and that it was completed then and there. What it does not say is that we must each morning get up and “crucify ourselves again to sin.” Instead, it says that by God’s judicial act, not by our experiential effort, the old man was “crucified” and therefore “destroyed.”