For if you live according to the sinful nature, you will die; but if by the Spirit you put to death the misdeeds of the body, you will live. Romans 8:13 (NIV)
Here is truth: the longer we stay in contact with our former way of life and the sin it contained, the more corrupt we will become. We are told to “put off”and “throw off” our former conduct. This implies stripping off, or flinging it far away, as though it were that rotting corpse. Accompanying putting off the old man is being renewed in the spirit of the mind:
Instead, there must be a spiritual renewal of your thoughts and attitudes. Ephesians 4:23 (NLT)
The Word and Spirit supply what is needed to renew the mind (Rom 12:1-2). This is inseparably coupled with changed living and enables us to understand, believe, and obey.
…you have stripped off your old evil nature and all its wicked deeds. In its place you have clothed yourselves with a brand-new nature that is continually being renewed as you learn more and more about Christ, who created this new nature within you. Colossians 3:9b-10 (NLT)
When we become a Christian, God gives us a completely new spiritual and moral capacity that a mind apart from Christ could never achieve (1 Corinthians 2:9-16). The mind is the center of thought, understanding, belief, desire, and motivation. This is why it is critical to begin to renew your mind with His Word.
It is not adequate to just change behavior because what drives the behavior is still the same. Our mind must be retrained to operate biblically so that when we are presented with the same old temptations, we think a new response. Instead of, “If I tell the truth, I am going to be in trouble,” the new thought will become, “Telling the truth is the way I will honor God, even if it means I am disciplined. It is more important to be honest than it is to look good or escape being disciplined.”
We cannot assume that new thinking alone will lead to walking worthy and new living. We must also deal with what is standing in the way of belief and action. Genuine change is more than stopping wrong behavior; there must be repentance which includes an understanding that the actions are not glorifying to God; there must be a change in the manner of life that we live. Genuine repentance is accompanied by a desire to obey. We cannot separate thinking from obedience-they are inseparable.
And remember, it is a message to obey, not just to listen to. If you don’t obey, you are only fooling yourself. For if you just listen and don’t obey, it is like looking at your face in a mirror but doing nothing to improve your appearance. You see yourself, walk away, and forget what you look like. James 1:22-24 (NLT)
When Jesus Christ is the ruler of our heart (inner man), our thoughts, understanding, beliefs, desires, and motivations flow from what He wants us to do as seen in His Word.
You must display a new nature (put on the new self, put on the new man) because you are a new person, created in God’s likeness—righteous, holy, and true. Ephesians 4:24 (NLT) (verse quoted with my additions)
This indicates a change of our entire life-style. Real change begins in the heart and overflows into our lives where Christ is reflected in us.