When man strives in the futility of his mind there are one of two outcomes, self righteous legalism or immoral abandon.
Believing that we need to be righteous in order to be accepted by God, and thinking that we can achieve it by our own efforts leads to systems of belief that are full of dos and don'ts. The Pharisees in Jesus' day were a sect who went beyond the law of God to create rules that were so stringent that no one could ever live up to the expectations. They didn't even live up to them. We call people who say they are one thing but do another pharisaical.
Self righteous people begin to see their rules as normative and start to judge others for not living by them. They create communities of like minded individuals and then shun those who don't agree. When Paul went to the gentile world the Judaizors followed and tried to force religious rules on new converts telling them they weren't "real" Christians unless they conformed. We have groups like that today who look down at people with tattoos, long hair, women with make up or who wear pants. We are too much like the world if we drive cars or use electricity. Smoking and drinking are the greatest of sins. Music, language, movies, define the state of our righteousness, and the list goes on.
The most extreme example in our day are Muslims, who not only created a system of beliefs based on works but will force others to believe or die. Self righteous superiority always leads to law and condemnation.
However, the extreme occurs when striving alienates us from God because of our continual failure. Man gives up and creates systems of belief that abandon moral restraint. His heart becomes hard toward God and he gives himself over to sensuality. They believe that what is done in the flesh doesn't matter and that feeding its appetites is freeing. They justify greed, the rationalize pornography, they legitimize homosexuality, they condone divorce, they chase after pleasure, they neglect the poor, and they are "greedy to practice every mind of impurity."
In Ephesians 4:19 the term impurity has a religious connotation. It's an impurity that defiles the sanctuary of God. Those who have hardened their hearts are greedy to do anything that demeans, defiles, or denies the things of God. Christians do these things in the dark, the Gentiles of the world do them in the light. If you don't agree with and accept their behavior you are a ___ophobe. If you dare have standards of righteousness you are offensive. If you dare speak up for righteousness you are bigoted, condemning and unloving.
Man is more comfortable living at the extremes and will gravitate in the direction that makes them feel more secure. Striving in the futility of the world's mind will lead to either self righteous legalism or sensual greedy impurity. Your not like that in Christ. I'm just saying...
Eph. 4:19 "They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity."