Because they are callous, they have given themselves over to indecency for the practice of every kind of impurity with greediness.
Paul is continuing his description of the unregenerate. He said they are callous after saying their hearts are hardened.
The one who says, “I feel nothing; nothing makes me cry,” should watch it. Even Jesus wept (John 11:35). The person who says nothing moves me should watch out. Is that not a sign of callousness?
Is it not like Psalm 14:1, which says that fools say to themselves, “There is no God”?Sometimes when we hear the word fool, we think it is the incompetent; that’s the simple. But the fool is willfully going in the wrong direction and would not be convinced otherwise. It is where the act of wilfulness against God lands him that is the issue. A fool is truly one from the standpoint of God (Luke 12:20), as it is written, the wisdom of this age is foolishness with God (1 Corinthians 3:19).
Remember, Paul is still on the topic of how the Gentiles live that he began in verse 17.
He traced it to ignorance. Meaning some people will think they are wise and informed, but they are not.
He traced it to futile thinking, meaning there is no way to remove our thinking from our actions.
He traced it to a darkened understanding, and darkness represents the operations of Satan. In another place, he mentioned the spirit working in the children of disobedience (Ephesians 2:2).
He traced it to a hardened heart, meaning instead of being sensitive to what God wants and what will help others, they are insensitive; in short, they have no conscience, nothing in them for correction. That accounts for their having given themselves over to indecency, for the practice of every kind of impurity with greediness, in a never-ending cascade, with no natural possibility of turning back.
Remember, Paul started by saying, "Don't live like that." That means it is not automatic for Christians not to live like that, so they need to be told not to.
Christians need to be told what not to do. And Paul's letter is sprinkled with those instructions; Christians are not supposed to be left to their own devices in the name of grace.
My brothers and sisters, if anyone among you wanders from the truth and someone turns him back, he should know that the one who turns a sinner back from his wandering path will save that person’s soul from death and will cover a multitude of sins.
That is a Christian who had wandered away from the way, from the truth.
Brothers and sisters, if a person is discovered in some sin, you who are spiritual restore such a person in a spirit of gentleness. Pay close attention to yourselves, so that you are not tempted too.
There is no need to try to say what Paul is saying is not really sin in the moral code sense.
It is unfortunate that people want to redefine sin now that we are Christians, as if God has changed, and sin is no longer sin, as if the only sin is the supposed negative confession of saying you are a sinner.
They make a lie a whole swath of the writings of Scripture. Those are people whose mouths must be stopped (Titus 1:11). They are the people that Jude warned against.
For certain men have secretly slipped in among you—men who long ago were marked out for the condemnation I am about to describe—ungodly men who have turned the grace of our God into a license for evil and who deny our only Master and Lord, Jesus Christ.
They may say Jesus is Lord, but they clearly deny his masterness over us. They have a Jesus who is as soft as foam that they throw around and bend to their whims. But they have no way of escape because Jesus spoke clearly against sin in His letter to the churches after He was resurrected.
Indecency talks about shamelessness; greediness is about excess; impurity is how God sees it, and the giving of yourself to it means this is your new identity; that is what you identify as.
We see this in our days, where cohabiting is seen as nothing, and stealing government funds is seen as smart and a survival tactic.
And it comes from being callous, a wrong bent of the thinking process away from the light to darkness, hence the darkened understanding.
Writing to Christians, the writer of the book of Hebrews warned against the deceitfulness of sin.
See to it, brothers and sisters, that none of you has an evil, unbelieving heart that forsakes the living God. But exhort one another each day, as long as it is called “Today,” that none of you may become hardened by sin’s deception.
And again, sin should not be defined narrowly in the name of the bible context. The writer used the word "sin" and was not inviting us to narrow it to a lack of belief alone.
Remember that when it comes to sin, the response in the Old Testament was sacrifice; now Jesus has offered a once-and-for-all sacrifice, but sin is still sin.
So rather than a new sacrifice every day, the writer of the book of Hebrews urges exhortation every day, just as John urged confession to God for forgiveness (1 John 1:9), and just as Paul in this passage is exhorting, saying he is insisting in the Lord that the people no longer live the way the Gentiles live (Ephesians 4:17).
By redefining sin, they cannot warn of temptation.
These are wolves in sheep's clothing (Matthew 7:15).