What is Sin

What Is Sin?

If sin is as serious as Scripture teaches, then we first need to understand what sin actually is. The word is commonly associated with immoral behavior, wrongdoing, or the violation of God’s law. Those descriptions are not necessarily wrong, but they can be incomplete if they leave us thinking of sin only as an outward act, or if the standard of what is moral and immoral is left to the judgment of individuals, cultures, or societies.

A society can change its moral standards. What one generation condemns another may accept, and what one culture considers reprehensible another may tolerate or even celebrate. Our consciences can likewise be influenced, dulled, misinformed, or ignored. Therefore, neither individual opinion nor social consensus can finally determine what is and is not sin. If sin is ultimately a transgression against God, then God—not mankind—must be the One who defines it.

The Standard Belongs to God

Scripture presents sin in relation to the character, will, and moral standard of God. Sin is not merely whatever human beings happen to regard as objectionable. It is any deviation from God’s revealed will, whether by openly opposing what God commands or by failing to conform to what He requires.

1 John 3:4: “Everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness”.

To describe sin as lawlessness is therefore to describe a failure to conform to God’s moral law. That failure can be active or passive. It can involve doing what God has forbidden, refusing to do what God has commanded, or falling short of the righteous standard He has revealed.

Romans 3:23: “For all have sinned and fall short of the glory of God”.

For this reason, I believe a useful working definition of sin is this: sin is any thought, attitude, motive, word, action, or failure to act that is contrary to, or falls short of, the revealed will and moral character of God.

That definition is much broader than simply describing sin as doing something society regards as immoral. It places the standard where Scripture places it—with God.

Sin Is More Than an Outward Act

One of the great dangers in thinking of sin merely as an immoral act is that it can lead us to look almost exclusively at outward behavior. Scripture does not permit us to make that distinction. Sin involves what we do, but it can also involve what we think, what we desire, what we say, why we do something, and what is taking place within the heart.

Jesus made this particularly clear when He addressed adultery. The physical act is sinful, but Christ did not allow His hearers to conclude that a person who had refrained from the outward act was therefore necessarily innocent of the sin within.

Matthew 5:27-28: “You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart”.

The same principle appears when Jesus explains that evil proceeds from within the person.

Mark 7:20-23: “What comes out of a person is what defiles him. For from within, out of the heart of man, come evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, foolishness. All these evil things come from within, and they defile a person”.

Sin therefore cannot be reduced to visible acts which can be separated from the person who commits them. Scripture reaches inward to the heart, mind, desires, attitudes, intentions, and motives from which our outward behavior proceeds.

Even a Good Act Can Be Done Sinfully

Because God judges more than outward behavior, it is even possible to perform an outwardly good action for a sinful reason. Someone may give generously, serve another person, pray publicly, or perform some other admirable act while being motivated primarily by pride, recognition, self-glorification, or the desire to appear righteous before others. The outward act may conform to the letter of what is right while the motive behind it falls short of the spirit in which it ought to have been done.

Jesus warned against precisely this kind of righteousness when He spoke of those who gave to the needy in order to receive praise from other people.

Matthew 6:2: “Thus, when you give to the needy, sound no trumpet before you, as the hypocrites do in the synagogues and in the streets, that they may be praised by others”.

This demonstrates why a biblical understanding of sin must include motive. God is not merely concerned with whether we performed the correct outward action, but with the heart from which that action proceeded.

Sins of Commission

A sin of commission occurs when we do what God has told us not to do. Lying, stealing, adultery, murder, idolatry, slander, envy, deceit, and countless other sins fall within this category. In these cases, God has revealed what is wrong and the person acts contrary to His command.

Scripture provides many examples:

Romans 1:28-31: “And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done. They were filled with all manner of unrighteousness, evil, covetousness, malice. They are full of envy, murder, strife, deceit, maliciousness. They are gossips, slanderers, haters of God, insolent, haughty, boastful, inventors of evil, disobedient to parents, foolish, faithless, heartless, ruthless”.

Galatians 5:19-21: “Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these”.

These lists are not intended to provide every possible example of sin. Rather, they demonstrate how broadly sin can manifest itself—in actions, relationships, speech, attitudes, desires, loyalties, and dispositions of the heart.

Sins of Omission

Sin is not limited to doing what God has forbidden. We can also sin by failing to do what God has commanded or what we know is right. This is commonly described as a sin of omission.

A person can therefore violate God’s will not only by doing evil but also by refusing to do good. We can fail to love, fail to forgive, fail to show mercy, fail to defend what is right, fail to help when help is within our ability, or knowingly remain silent when faithfulness requires us to speak.

James 4:17: “So whoever knows the right thing to do and fails to do it, for him it is sin”.

This distinction between commission and omission is important because it prevents us from measuring righteousness merely by the bad things we have managed not to do. A person might say, “I have never murdered anyone, stolen anything, or committed adultery,” while overlooking the many things God required that he failed to do. Biblical righteousness involves more than avoiding evil; it also involves doing what is right.

Sin as Rebellion and Rejection of God

Scripture describes sin in several different but complementary ways. One of the most fundamental is rebellion against God. Sin rejects God’s rightful authority and substitutes another authority in His place—very often ourselves.

For this reason, sin may rightly be described as rebellion, rejection, or even mutiny against God. Whenever we knowingly place our judgment above His, distrust what He has said, refuse what He commands, or choose something contrary to His will, the problem is deeper than merely breaking an isolated rule. We are challenging the rightful authority of the One who gave the rule.

Sin therefore has a relational dimension. It is not merely that a law has been violated; the Lawgiver Himself has been dishonored.

Sin as Idolatry

Sin can also be understood as idolatry—placing something created in the position that properly belongs to God. Idolatry is not limited to bowing before a carved image. Anything that receives the trust, devotion, allegiance, worship, or priority that belongs foremost to God can become an idol.

This is why the biblical struggle with idolatry reaches much deeper than ancient statues and pagan temples. At its root, idolatry is a disordering of our love and loyalty. Something other than God is allowed to occupy God’s rightful place.

Matthew 6:24: “No one can serve two masters, for either he will hate the one and love the other, or he will be devoted to the one and despise the other”.

Sin as Adulteration

Another way I find helpful to describe sin is as an adulterant. An adulterant is something introduced into what is pure that contaminates, corrupts, or makes it impure. The word is closely related in meaning to impurity, and it provides a useful picture of what sin does within our relationship with God.

Lack of trust, disloyalty, rebellion, unfaithfulness, rejection, deception, and falsehood are all adulterants within a relationship. A relationship built upon love, truth, trust, and faithfulness is damaged when something contrary to those things is introduced into it.

This relational picture is particularly appropriate because Scripture repeatedly uses marital unfaithfulness to describe man’s unfaithfulness toward God.

Jeremiah 3:20: “Surely, as a treacherous wife leaves her husband, so have you been treacherous to me, O house of Israel, declares the LORD”.

James similarly uses the language of adultery when describing friendship with the world in opposition to God.

James 4:4: “You adulterous people! Do you not know that friendship with the world is enmity with God?”.

This helps us understand why sin is far more personal than the simple violation of an impersonal statute. God is not merely a lawgiver sitting at a distance recording infractions. Scripture presents God as the One to whom love, trust, allegiance, worship, and faithfulness are owed. Sin adulterates that relationship through distrust, disloyalty, falsehood, rebellion, and misplaced love.

It takes two to establish a relationship, but only one party acting unfaithfully can damage it. This is why the biblical language of adultery, betrayal, rebellion, and idolatry is so fitting when describing sin.

Sin Is Anything Contrary to God

I have heard sin explained in many different ways, many of which correctly emphasize a particular aspect of it. Yet one of the simplest ways I personally think about sin is as anything and everything that is contrary to God.

God is true; sin embraces falsehood. God is faithful; sin is unfaithful. God is holy; sin brings impurity. God is righteous; sin is unrighteousness. God is worthy of our foremost love and trust; sin directs that love and trust elsewhere. God commands what is good; sin either does what He forbids or refuses what He commands.

These are not competing definitions of sin. They describe the same reality from different perspectives. Sin is lawlessness because it violates God’s law. Sin is rebellion because it rejects God’s authority. Sin is idolatry because it places something else where God belongs. Sin is unfaithfulness because it betrays the One to whom our faithfulness is owed. Sin is adulteration because it introduces impurity into what ought to remain holy. And sin is falling short because it fails to conform to the righteous standard of God.

Are All Sins the Same?

To say that every sin is a violation of God’s moral standard does not necessarily mean that every sin is identical in seriousness, consequence, or harm. Scripture itself recognizes distinctions. When Jesus stood before Pilate, He spoke of one who had committed a greater sin.

John 19:11: “Therefore he who delivered me over to you has the greater sin”.

Some sins plainly produce greater earthly harm than others, involve greater knowledge or intention, affect more people, or carry more severe consequences. Murder is not identical in its earthly consequences to an angry thought; nevertheless, neither should we use these differences to persuade ourselves that the sins we consider smaller are therefore harmless or acceptable to God.

James makes the important point that God’s law cannot be divided in such a way that obedience in many areas makes rebellion in another irrelevant.

James 2:10: “For whoever keeps the whole law but fails in one point has become guilty of all of it”.

The point is not that every individual sin is morally identical, but that no sin can be defended merely by comparing it with something worse. We stand accountable before God for our own sin.

Jesus therefore warned against becoming experts in another person’s failures while remaining blind to our own.

Matthew 7:3-5: “Why do you see the speck that is in your brother’s eye, but do not notice the log that is in your own eye? Or how can you say to your brother, ‘Let me take the speck out of your eye,’ when there is the log in your own eye? You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your brother’s eye”.

Recognizing degrees of seriousness should therefore never become an excuse for self-righteous comparison. One person’s greater sin does not make my lesser sin righteous.

A Working Biblical Definition

Bringing these descriptions together, sin should not be understood merely as committing particularly shocking or socially unacceptable acts. Scripture presents something much broader and much deeper.

Sin is any thought, attitude, desire, motive, word, action, or failure to act that violates, opposes, rejects, or falls short of God’s revealed will and righteous character. It includes what we do and what we refuse to do; what others can see and what remains within the heart. It is lawlessness toward God’s standard, rebellion against His authority, idolatry when something takes His rightful place, unfaithfulness toward the One worthy of our trust and love, and an adulteration of the relationship humanity was created to have with Him.

Understanding sin this way is important because it prevents us from reducing it to a list of particularly offensive behaviors committed by other people. Before Scripture ever allows us to ask how sinful someone else may be, it forces us to look inward. The question is not merely whether we have avoided society’s worst offenses, but whether our hearts, motives, words, actions, loyalties, and omissions have perfectly conformed to the will of God. They have not—and that is why the problem of sin reaches every one of us.