The structure of sin in the human personality is something far more complicated than the isolated acts and thoughts of deliberate disobedience commonly designated by the word. In its biblical definition, sin cannot be limited to isolated instances or patterns of wrongdoing; it is something much more akin to the psychological term complex: an organic network of compulsive attitudes, beliefs and behavior deeply rooted in our alienation from God. Sin originated in the darkening of the human mind and heart as man turned from the truth about God to embrace a lie about him and consequently a whole universe of lies about his creation. Sinful thoughts, words and deeds flow forth from this darkened heart automatically and compulsively, as water from a polluted fountain. "The Lord saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.” (Genesis 6:5) This is echoed in Jesus's words: "Either make the tree good, and its fruit good; or make the tree bad, and its fruit bad; for the tree is known by its fruits. You brood of vipers! How can you speak good, when you are evil? For out of the abundance of the heart the mouth speaks. The good man out of his good treasure brings forth good, and the evil man out of his evil treasure brings forth evil.” (Matthew 12:33-35)
The human heart is now in a reservoir of unconscious disordered motivation and response, of which unrenewed persons are unaware if left to themselves, for "the heart is deceitful above all things, and desperately corrupt; who can understand it?” (Jeremiah 17:9) It is as if they were without mirrors and suffering from tunnel vision: they see neither themselves clearly nor the great peripheral area around their immediate experience (God and supernatural reality). At the two most crucial loci of their understanding, their awareness of God and of themselves, they are almost in total darkness, although they may attempt to remedy this by framing false images of themselves and God. Paul describes this darkness of the unregenerate mind: “now this I affirm and testify in the Lord, that you must no longer lives as the Gentiles do, in the futility of their minds; they are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to the hardness of heart.” (Ephesians 4:17-18) The mechanism by which this unconscious reservoir of darkness is formed is identified in Romans 1:18– 23 as repression of traumatic material, chiefly the truth about God and our condition, which the unregenerate constantly and dynamically “hold down.” Their darkness is always a voluntary darkness, though they are unaware that they are repressing the truth.
Richard Lovelace, Dynamice of Spiritual Life, p. 88-89.