That you put off, concerning your former conduct, the old man which grows corrupt according to the deceitful lusts, and be renewed in the spirit of your mind, and that you put on the new man which was created according to God, in true righteousness and holiness.
Listen to the "Verse by Verse" episode covering this scripture.
God calls Christians to get rid of their old, sinful way of life, and to replace it with a new life and way of thinking made possible by the Holy Spirit living in us.
The “old man” is symbolically buried in water baptism, and the “new man” is given life through the laying on of a true minister’s hands and the receiving of the Holy Spirit.
Paul also called this process being “transformed by the renewing of your mind” (Romans 12:2).