This question is of vital importance because of the fearful judgment against those who commit sin. “The soul that sinneth, it shall die,” thunders the Old Testament (Ezekiel 18:20). In like tones, the New Testament declares: “The wages of sin is death” (Romans 6:23). The one who lives in sin throughout his earthly life and faces God without having obtained divine forgiveness will be sentenced to eternal perdition.
Sin sprang full-grown among men. Adam and Eve sinned by disobeying God. The first boy born on this earth grew to manhood and murdered the second, his own brother! And sin has existed in every generation since.
In our time, however, there is one difference: many no longer know what sin actually is. Things evil are sometimes designated as good; things good, as evil. Isaiah condemned such a practice, declaring, “Woe unto them that call evil good, and good evil” (Isaiah 5:20).
Since this confusion exists, and since a person will not seek forgiveness for sin until he knows what sin is, a clear-cut definition, both negative and positive, is urgently needed.
SIN IS NOT NECESSARILY CRIME
Some equate sin with crime, feeling that to commit sin one must be a murderer, robber, rapist, or the like. Once, an evangelist passing out revival circulars was told that he should go to the local jail and try to convert a woman who had recently murdered her father. Certainly this woman needed forgiveness, but no more so than other sinners who had not committed a crime.
A crime is a sin, but not every sin is a crime. Crimes are committed against people; sin is committed against God. As an example, David wronged Bathsheba, and committed the crime of murder against Uriah her husband; but he affirmed, “Against thee [God], thee only, have I sinned” (Psalm 51:4).
SIN IS NOT UNBELIEF ALONE
Near the end of His ministry, Jesus told His disciples that the Holy Ghost would “reprove the world of sin . . . because they believe not on me” (John 16:8-9). Misinterpreting His meaning, some have concluded that sin is nothing more than unbelief. But Jesus meant that unbelief would form the basis of sin. People sin because they do not believe on Jesus Christ. Unbelief is sin, but it leads to further sin.
“SIN IS THE TRANSGRESSION OF THE LAW”
This definition is given in I John 3:4. By law, the apostle meant the Word of God, which originally was the Old Testament but which now includes the New Testament as well. Sin, then, is the transgression (breaking) of a commandment found in the Bible.
Sins of Commission. Someone is guilty of such a sin when he does something that the Word of God forbids.
Sins of Omission. He who fails to do what he knows God has commanded is guilty of a sin of omission. “To him that knoweth to do good, and doeth it not, to him it is sin” (James 4:17).
“ALL UNRIGHTEOUSNESS IS SIN”
I John 5:17 declares this truth. A person is unrighteous when he does what is wrong. According to this verse, then, when someone does wrong, he commits sin.
We should note that all unrighteousness is sin. Men are prone to classify sin as little or great, black or gray, mortal or venial. But to God, all sin is offensive and objectionable. As an example of the difference between man’s and God’s judgment of sin, man classifies the sin of lying as one of the lesser evils, but God places “all liars” in the same category as the abominable, murderers, whoremongers, sorcerers, and idolaters (Revelation 21:8). Moreover, He pronounces the same judgment upon all of these sinners, eternal perdition in the lake of fire and brimstone.
What then is sin? Simply put, sin is doing what God forbids or failing to do what He commands.
Taken from the Word Aflame Press Tract – “What Is Sin?” – #1567220711