"Ephesians 4:22 commands Christians to ""lay aside the old self which is being corrupted by the lusts of deceit."" The old idolatrous self pursued desires outside of the parameters of God. Lusts of deceit typically promise immediate gratification but hide costs over the long term, resulting in repetitive satisfaction of seemingly innocuous lusts. Corruption nevertheless sets in. Repetition ossifies lusts, and the old self is practically defined by the lust which is now an habitual practice. The periodic drinker becomes a drunkard, the occasional gossiper an egregious slanderer, the ""recreational user,"" a full blown drug-addict. The costs are now plainly evident, but the fool characteristically doubles down, and rationalizes his slavery. (""I can quit anytime I want, he loudly protests"") The fool originally contracted the lusts of deceit to serve the old self; now lusts are the master and the old self the servant, who has been thoroughly corrupted by the lusts of deceit. The Scriptures address this root of deception: ""The foolishness of fools is deceit."" (Proverbs 14:8) The practice of engaging lusts (foolishness) among fools reinforces self-deception. In any event, the foolishness of fools doesn't instantly leave when saints confess Christ. The episode notes that the old self is presently BEING corrupted by the lusts of deceit. All Christians are in the process of sanctification in which the Holy Spirit helps the believer identify with the new man in Christ, which is ""created in righteousness and holiness of the truth."" (24) This identification founded on TRUTH is the antidote to the DECEIT of fools. Believers then must regularly put on Christ, while they lay aside the old self, making no provision for the flesh in regard to its lusts. (Romans 14:17)
The Depraved Mind, a Servant of Lusts
The fool's hostility to the knowledge of God leads to a mind that no longer serves its original purpose, that of discovering the works of God and co-laboring with Him, giving Him glory. The depraved mind of a fool instead serves a different purpose, the advancement of an idol god largely defined by unrestrained lusts. This episode unpacks the usurpation of the mind in service of idolatry. Paul notes that unbelieving Gentiles "walk, in the futility of their mind, being darkened in their understanding, excluded from the life of God because of the ignorance that is in them, because of the hardness of their heart." (Ephesians 4:18) Working backwards through the quote, Gentile hostility to the knowledge of God, based on "hardness of heart" makes them ignorant and disqualifies them as participants in the life of God. Without the knowledge of God (deliberately suppressed), the mind can't possibly serve its original purpose. The understanding is darkened, the mind itself a futile faculty, cut off from the life of God. The consequent "depraved mind" exists to service the idol identity grounded in the big three ("the lusts of the flesh, the lusts of the eyes, and the boastful pride of life"--1 John 2:16) "Sensuality for the practice of every kind of impurity with greediness" (Ephesians 4:19) is relatively easy, for the conscience, acting on the inner law of God, has been largely deactivated. The Holy Spirit has given the fool over to a depraved mind that is "callous" and resistant to correction. The litany of character defects in Romans 1:29-31 is predictable: "full of envy, murder, strife, deceit, malice, gossips, slanderers, haters of God, insolent, arrogant, boastful, inventors of evil, disobedient to parents, without understanding, untrustworthy, unloving, and unmerciful."