EPHESIANS4 vv17-19.

God's verdict on the truth about human nature         (17-19)

Scripture is clear, there is no betterment for it, no improvement, no reformation, God is finished with the old man. Those He saves are a new creation, not that He makes us better, but that He makes us anew.   In John 3v6-7, Jesus said to one of the foremost spiritual leaders of Israel  " that which is born of the flesh is flesh, and that which is born of the Spirit is spirit.   Marvel not that I said unto thee, ye must be born again."   In Ephesians 2v2-3, Paul has reminded them that their former way of life was under the dictates of a godless world, of corrupt flesh, and demonic spirits.   Now he says  "walk not as other Gentiles walk" and he brings the Lord as a testimony to this;  in effect he brings the Christian under a vow to turn away from their former life.   He now goes on to explain why.

1. The vanity of their mind.   This means emptiness of mind, not emptiness intellectually but emptiness spiritually.   In the book of Ecclesiastes king Solomon, the most prosperous and wisest man in all the earth, wrote these words as a summary of the best of human life.   "All is vanity and vexation of spirit."   No matter how much we human beings seek to substitute the real need within us with lesser things, we are left with emptiness.   The truth of this is illustrated in the name Golgotha, where Christ was crucified.   Golgotha means the place of a skull, and the message is clear that, without God, human beings are bereft of true wisdom, so far as God is concerned, just an empty skull. 
2. Having the understanding darkened.   A derogatory yet true description.... like toads living in a darkened cavern thinking this is all there is.   The condition of vanity of mind is because the mind has been darkened by an evil force and therefore unable to see properly.   The Lord Jesus dealt with this in Matthew 7v22-23  "the light of the body is the eye; if therefore thine eye be single, thy whole body shall be full of light.   But if thine eye be evil,   thy whole body shall be full of darkness.  If therefore the light that is in thee be darkness how great is that darkness!"   In John 3v19 he gives another dimension to this  "this is the condemnation that light is come into the world and men love darkness rather than light."   Not only were we in darkness but we preferred the darkness to the light that God would give us.   God therefore calls the human condition one of darkness.  
3. Alienated from the life of God.   God, who gave us life, is life and there is no life worth talking about apart from Him.   In John 17v3 Jesus described eternal life, real life, as "knowing God and Jesus Christ whom God sent.   "The life of God" is life that is far superior to anything that this darkened world can provide: in essence a human being can be satisfied with nothing less than God.   The expression "get a life" is a statement of some arrogance since it usually points to things lesser than God for their occupation.   The only ones who have a life are those who know God and Jesus Christ who is the creator of all life.  
4. Through the ignorance that is in them.   Professing wisdom they prove themselves to be fools.   Scripture is clear "the fear of the Lord is the beginning of wisdom." (Proverbs 9v10)   Those who have not even started on the road of reverential fear of the Lord, accepting His judgments upon us, confessing our sins before Him and trusting only in Christ for salvation, are deemed by God to be living in ignorance, and because of that they think that the shallow lives that they are living is all that exists.
5. Because of the hardness  (R.V.) of their heart.   Rejected light brings an ever increasing hardness of heart to the things of God.   The same sun that melts ice, hardens clay.   When bones are broken in the human body there forms a substance called "callus"  which sets and joins the bones together.   The result makes the join harder than the actual bone itself.   What is a benign process for the human body is an evil process in the human heart because the heart is hardened towards God and that process gets harder and harder with time.   The heart is much more than the fleshy pump which keeps our bodies alive.   In the bible the heart is the very centre of the human being, the centre of the will, the driving force, that which makes us all that we are.   When all that we are is hardened toward God, there may come a time when God will finally accept our decision against Him.
6. Who being past feeling have given themselves over unto lasciviousness.   The word asalgeia which translates as lasciviousness is the ultimate condition reached when the conscience has been so supressed that it leads to a person throwing off all restraint.   This is the end of the process where there is no longer any attempt to cover up, abandoning all morality resulting in a state of amorality.   The process is from immorality (where all of us have been) to amorality, where open sin has become a way of life.   This inevitable process leads to the constant breaking of the two major commandments, namely, living a life of uncleanness in the sight of God, and living to defraud my fellow man.   This is the sure end of a life lived without God.

This is how the nations live who know not the Lord.....says Paul "do not live your lives like that!"