Colossians 3: 5--6 Put to death, therefore, whatever belongs to your earthly nature: sexual immorality, impurity, lust, evil desires and greed, which is idolatry. 6 Because of these, the wrath of God is coming
A believer is a new creation( 2 Corinthians 5:17). This is an incontrovertible truth. In Christ, the believer is not a refurbished being neither is he a rehabilitated being. He is a regenerated and recreated being. He had a form before meeting Christ but in Christ, he's made new. This is one of the wonders of God's marvelous grace.
Apostle Paul says, "We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin"(Rom6:6 ESV).
Now, we have a new self that is created after the likeness of God: "And to put on the new self, created after the likeness of God in true righteousness and holiness" (Eph4:24). A believer is a new man.
While we know from Pauline revelation that the believer is new and created after the likeness of God in true righteousness and holiness, Paul said, "PUT TO DEATH, therefore, whatever belongs to your EARTHLY NATURE: sexual immorality, impurity, lust, evil desires and greed, which is idolatry. 6 Because of these, the wrath of God is coming" (Col3:5-6).
Paul was talking to believers, new creations who had the nature of God, he is saying they should put to death their earthly nature. If the earthly nature is absent or gone totally at salvation, he wouldn't have instructed they put it to death yet these were new creations being addressed here. We need to know what this earthly nature is and be sure there's no mix up somewhere.
Man is a tripartite being made up of spirit, soul and body (1Thes5:23). When you came to Christ, it is your spirit man that became new and regenerated not your soul( mind, will and emotions)or body. The information (good or bad) in your mind weren't formated.
Obviously, the earthly nature that must be put to death are the carnal tendencies that exist in your mind not your spirit. Apostle Paul knowing this enjoined Roman believers saying, "Do not conform to the pattern of this world, but be transformed by the RENEWING OF YOUR MIND. Then you will be able to test and approve what God’s will is—his good, pleasing and perfect will" (Romans 12:2 NIV).
You don't say "I'm a new creation so I'm not concerned about what goes into my mind". While your spirit is new, your mind requires daily renewal through the word. That way, you begin the process of putting to death the earthly nature. Don't neglect that earthly nature in you, put it to death.
Father, I receive the grace to put my earthly nature to death in Jesus name.