It's indeed an incredible irony. While we have the works salvation crowd who mocks the doctrine of eternal security which states that one can know for sure they are permanently secure in Christ as nothing more than a license to sin, however many of their followers are actually living sinfully. Many of them are drunkards, adulterers, homosexuals, extortioners, thieves, revilers, backbiters, etc. in their lifestyle. Why is that? Now it's time to discuss some reasons why:
1.) They are trying to establish their own righteousness (Romans 10:3)
Works salvation is nothing more than trying to establish one's own righteousness and being ignorant of the righteousness of God. One has to realize that the Law of God is the real standard for righteousness, not weighing good works vs. bad works. Unfortunately since they are trying to achieve righteousness their way (which Proverbs 14:12 says is the way of death) their standard is based on self vs. others, not God's Law vs. them. Christians on the other hand are counted for righteousness not by their works but God's justification of them results to good works (Romans 4:5). This kind of mentality can be found in Isaiah 30:1 where the people take counsel but not of God so they may add sin to sin. Isaiah 64:6 is indeed clear that man's righteousness is but filthy rags which of course means tainted with sin. Romans 3:10-13 calls all man not righteous and being very sinful.
2.) They are fallen from grace (Galatians 5:4)
Those who attempt to be justified by the Law are fallen from grace. Titus 2:11-15 and Ephesians 2:10 teaches that God's grace results to righteous living. Philippians 2:13 credits God for working in the believer. On the other hand, these people are trying to do the impossible- to get justified by the Law. A well-known commentary said, "Do you think that's easy to carry your cross, choose Jesus over your parents, give all to the poor and keep the whole Law in order to merit Heaven? No. That's not easy. In fact, salvation is impossible with man. But with God He makes all things possible."
3.) It's a matter of pride (Ephesians 2:8-10)
Ephesians 2:8-10 draws the line between the believer doing good works vs. the unbeliever doing good works. The Christian says, "Lord because I'm secure in you, I'll show my gratitude. Tell me what to do since you saved my soul. I want to be thankful." The unbeliever like the Pharisees say, "Lord I thank you that I am not like other people and I'm going to Heaven because I'm not like (insert names) and I don't (insert sins) and I (insert good works)..." nonsense. In short, John 12:43 says that they love the praises of men and not of God. There's nothing wrong with a Christian getting praised but he/she should return that praise to God and get no merit from it. They are too proud and too childish to accept the fact that they are lost sinners who need to believe on the Jesus Christ as their Lord and Savior in order to be saved. Romans 3:19 is clear with this fact that the whole world must shut up before God because the Law shows them guilty. Salvation is about mercy not justice.
4.) They were not sanctified by God (1 Corinthians 6:11)
While 1 Corinthians 6:9-10 mentions the very state of unsaved man (homosexuals, drunkards, adulterers, etc.) and labels them as unrighteous (well Romans 3:10-23 is clear about the fact that NOBODY is righteous by their own selves and that they are SINNERS), the next verse says that such were some of you meaning that's what they were before they were saved. Without God's washing, a rehabilitation is nothing more than an empty practice. Some have reformed in one way but continue to do new vices instead. Matthew 1:21 is clear in saying that Jesus came to save the people from their SINS. If they're not saved, they're not saved from their sins.
5.) They are relying on the flesh which produces wickedness (Galatians 5:19-20)
Galatians 5:19-20 is clear what the fruits of the flesh are: adultery, fornication, uncleanness, lasciviousness, 20Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, envyings, murders, drunkenness, revellings, and such like, these who do not inherit the Kingdom of God. Matthew 7:16-20 is clear that by the fruits they shall be known.
6.) There is an absence of chastising from God in their lives (Hebrews 12:5-7)
As said, if God does not chastise a person then He deals with them as outsiders and not sons. God chastises those who are His. The rest of the world is allowed to face the consequences of their own actions much later than the Christians are. Why? God wants to get Christians back on track (and they get back on track). As for them, He never knew them (Matthew 7:21-23).
7.) They deny God in action (Titus 1:15-16)
Their actions speak louder than words. John 12:43 can come to mind again as they deny God in action. They deny God in action with their good works only for the crowd and not for God. Many of them do good works in front but live so sinfully behind the backs of their beneficiaries. Many philanthropists can be seen giving much to the poor and attending religious services yet they are having all the extramarital affairs and cheating their own family behind their backs. As said, good works were not meant for boasting but for gratitude to God for salvation NOT for show business.
8.) They received knowledge of the truth but NEVER applied it (Hebrews 10:26-29)
Many people hear the Gospel of Jesus Christ but they never apply it, they never accept it in them. They just "received it" by hearing it but they later rejected it. In fact, when people continue to reject the Gospel of Jesus Christ which has His good news to salvation, they will continue living sinfully as a consequence. A good example is about how religious criminals are- they keep rejecting the Gospel and trusting in their good works (funny huh?) and in the end, they do more sin. They think they don't need the blood of Jesus that washes away all sin so they trample it as if it were an unholy thing. Again, they'll keep on sinning because they continue to reject the cure for sin- the Lord Jesus Christ!