What does it mean that sin is lawlessness?

from the old testament

• God is perfect, and His law is perfect. Therefore, His commands are holy, just, and good, and following them leads to life and blessing (Psalm 19:7–11; Deuteronomy 6:24). Breaking His good and perfect law is lawlessness.
• God declared a curse on those who failed to keep His law (Deuteronomy 27:26).
• God warned that disobedience brings judgment (Deuteronomy 28:58–59).
• God gave us the sum of the law in Deuteronomy 6:4–9 and Micah 6:8. In these verses, we are called to love Him wholeheartedly, walk humbly, act justly, and live in obedience to His commands as the foundation for righteous living. The law shows us what that looks like. The Mosaic Law, as given to the Israelites, were specific commandments God gave His people under a theocratic rule. These laws were to all point to God’s character and revealed people’s inability to live according to God’s standard. While the Mosaic Law was specifically how God called Israel to live, it ultimately pointed forward to Christ who fulfilled all aspects of the law.
• Israel was continually reminded to hear and obey the law (Deuteronomy 31:12). Sin is a failure to listen to and live by God’s law.
• In commissioning him to lead the Israelites, God commanded Joshua to meditate on the Book of the Law without turning from it (Joshua 1:8). Relishing and living by God’s ways would lead to success.
• Joshua urged Israel to hold fast to God’s law (Joshua 23:6).
• Psalm 1:2 tells us that the one who delights in God’s Word is blessed.
• David treasured God’s Word in his heart (Psalm 119:11), leading us to know and forsake sin and live according to God’s law, which brings life.

from the new testament

• First John 3:4 says, "Everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness." In the original Greek, the phrase "sin is lawlessness" would actually read more like "breaking the law is sin." This particular phrase is translated much better in the King James Version of the Bible which reads, "Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law."
• The Greek word used for "lawlessness" or "transgression of the law" is ἀνομία (anomia). The word means transgression or violation of the law or the condition of being without law either through ignorance or violation of the law. In short, sin is a transgression of the law. To sin is to violate the law. Those who violate the law sin. If a person makes a practice of sinning, then that person is making a practice of lawlessness, or of transgressing the law. Another way to look at this is that those who regularly go against God's ways (sin) are living as if there is no standard of righteousness (lawless). John further describes such people as "children of the devil" (1 John 3:10).
• The same word for lawlessness is used by Jesus in one of the most terrifying passages in Scripture: "Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, 'Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?' And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness'" (Matthew 7:21–23, emphasis added). These are people who clearly think they are Christians because of their good works, but Jesus says to them that they are actually workers of lawlessness (anomia). He does not know them, meaning they do not have a saving relationship with Him.
• Jesus uses the same term in one of His many "woes" to the Pharisees, saying: "Woe to you, scribes and Pharisees, hypocrites! For you are like whitewashed tombs, which outwardly appear beautiful, but within are full of dead people's bones and all uncleanness. So you also outwardly appear righteous to others, but within you are full of hypocrisy and lawlessness" (Matthew 23:27–28, emphasis added). This would have been especially hard for them to hear, considering that they prized themselves for following the law.
• In Matthew 23:27—28, Jesus is literally saying that the group of religious leaders who appear to be making the greatest effort to keep the Mosaic law are actually hypocrites who break the Mosaic law; they are full of lawlessness (anomia). This passage helps us to formulate a better understanding of lawlessness. After all, if the keepers of the law, the Pharisees, are accused of being transgressors of the law by the One who gave the law, namely Jesus, then clearly there is more to following the law than simply obeying the rules.
• The “Law” referred to in Matthew 23 is the Mosaic law—the more than six hundred commandments God gave to Israel after delivering them from Egypt (see Exodus 20—23; Leviticus; Numbers; Deuteronomy). Among these, the most well-known are the Ten Commandments (see Exodus 20:1–17; Deuteronomy 5:6–21).
• As Christians, we know that we “are not under law but under grace” (Romans 6:14–15; Galatians 3) because of the work of Jesus Christ on the cross. However, this doesn't mean that we are free from sin; and sin, as we have seen, is transgression of the law.
• When Jesus was asked what the greatest commandment is, He replied, "You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself" (Matthew 22:37–39; cf. Mark 12:28–34; Luke 10:25–37). Out of all of the 600+ rules and regulations within the Mosaic law, why would Jesus point to only these two? The reason is found in the next verse; "On these two commandments depend all the Law and the Prophets" (Matthew 22:40). Every law and everything that the prophets wrote about depends on loving God and loving mankind. This is "the Law"—to love.
• Matthew 24:12 warns us that lawlessness will increase in the last days.
• Before being saved by trusting in Jesus’ death and resurrection for the forgiveness of sins, we are all slaves to lawlessness (Romans 6:19).
• Jesus came to redeem us from all lawlessness (Titus 2:14).
• Jesus fulfilled the Mosaic law perfectly. Because of His death and resurrection, all who trust in Him are forgiven of their sins (Colossians 2:6–15; 2 Corinthians 5:17–21). We are made new and given the indwelling Holy Spirit. We are called to keep in step with the Spirit and follow the commands of Christ (John 15:1–17; Ephesians 4:17–32; Philippians 2:12–13).
• Paul tells us the sum of the law is to love (Galatians 5:14): "For the whole law is fulfilled in one word: 'You shall love your neighbor as yourself.'"
• When we are saved, the Holy Spirit lives within us and leads. He produces fruit that is actually in keeping with the intention of the Mosaic law (Galatians 5:16–24). Righteousness does not come from following the Mosaic law. Rather, it is by God's grace through faith in Jesus Christ (Ephesians 2:1–10; Galatians 3).

implications for today

Although we were all once slaves to lawlessness, when we are saved, we are freed from the bondage and eternal consequence of sin. Jesus paid the penalty for our lawlessness. While we still sin even after we are saved, we are no longer condemned and are empowered by the Holy Spirit living in us to pursue righteousness and grow in obedience to God’s law (Romans 6:6–7, 22; Romans 8:1–4; 1 John 1:7–9).

Jesus said, “This is the work of God, that you believe in him whom he has sent” (John 6:29). He also commanded, “Love one another as I have loved you” (John 15:12). Those who know Jesus learn to put sin to death; they are no longer under the Mosaic law, yet they do not live in lawlessness. Instead, they strive to live out their salvation, by God’s Spirit (Philippians 2:12–13). When believers sin, they repent, confident that God will cleanse them (1 John 1:6–10). A believer does not continue unrepentantly and without conviction in a lifestyle that celebrates and embraces sin—believers don’t live in lawlessness (1 John 3:4–10). While they will still sin, true followers of Christ make it their aim to please God and to live according to His ways. Those who claim to know God and yet do not follow His ways do not actually know God. They practice lawlessness rather than fulfill the law of Christ.