|What does such baptizing with water signify? It signifies that the Old Adam in us should, by daily contrition and repentance, be drowned and die with all sins and evil lusts and, again, a new man daily come forth and arise, who shall live before God in righteousness and purity forever. Where is this written? St. Paul writes, Romans, chapter sixth: We are buried with Christ by Baptism into death, that, like as He was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.|
According to the Bible, the old man or the Old Adam is our corrupt, sinful nature, which we have inherited from Adam and which will remain with us until we die. Everyone has an Old Adam.
Eph. 4:22: Put off, concerning the former conversation, the old man, which is corrupt according to the deceitful lusts.
Luther: “What is the old man? It is that which is born in us from Adam, angry, hateful, envious, unchaste, stingy, lazy, haughty, yea, unbelieving, infected with all vices, and having by nature nothing good in it.”