Is lying a sin? What does the Bible say about lying?

TL;DR:

Lying, whether small or big, is sin before God. God calls us to speak the truth in love and to walk in His truth.

Lying is a sin (Exodus 20:16) and has been a weapon of the enemy since the beginning of creation (John 8:44), as displayed in Genesis 3. The serpent (Satan), blatantly lies to Eve about God’s clear command not to eat of the fruit of the Tree of Knowledge of Good and Evil, telling her that she will “surely not die” if she disobeys God (verse 4). However, when she and Adam break God’s command, they—along with the whole world—suffer the consequences of their disobedience (verses 14-19). The Father of Israel, Abraham, lies to Pharaoh about his wife being his sister, and as a result, she is taken away from him to be wed by Pharaoh. When Pharaoh discovers she is Abraham’s wife, he confronts Abraham about his lie as it caused affliction on Pharaoh’s house (Genesis 12:18-20). Lies harm others. In Acts 5:3, show the tragic results that can come from lying. Proverbs 26:28 paints a vivid picture of harm a liar can do to his or her victims. As new creations in Christ, we must put away that which was part of our former life, including lying (Colossians 3:9). Instead of deceiving others, we should “put away falsehood” and replace it with truth (Ephesians 4:25).

from the old testament

From the earliest of times, lying was seen as sinful. This was evident in God’s condemnation and judgment of the serpent's lie in the Garden of Eden (Genesis 3).
When Abraham lied about Sarah being his sister instead of his wife, he almost lost her as a result. Instead, God intervened and rescued them from this situation, though it was clearly seen as wrong (Genesis 12:18-20).
Lying is listed as a sin in the Ten Commandments: "You shall not bear false witness against your neighbor" (Exodus 20:16).
Lying shows hate toward others. Proverbs 26:28 teaches, "A lying tongue hates its victims, and a flattering mouth works ruin."

from the new testament

Lying is ultimately the work of the Devil. Jesus taught, "You are of your father the devil, and your will is to do your father's desires. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies" (John 8:44).
Lying can bring God’s judgment. Acts 5:3 records Peter questioning two believers in the early church who had lied about an offering they made: "Ananias, why has Satan filled your heart to lie to the Holy Spirit and to keep back for yourself part of the proceeds of the land?" Both Ananias and his wife died that day due to their lie.
In contrast to lying, speaking truth shows love to our neighbors. Ephesians 4:25 shares, "Therefore, having put away falsehood, let each one of you speak the truth with his neighbor, for we are members one of another."
Lying is part of the "old self." Christians are called to stop lying. Paul wrote, "Do not lie to one another, seeing that you have put off the old self with its practices" (Colossians 3:9).

implications for today

Lying is the opposite of God's truth. First John 2:21 says, "I write to you, not because you do not know the truth, but because you know it, and because no lie is of the truth." Our words must not contradict what God says. Proverbs 18:21 states: “Death and life are in the power of the tongue, and those who love it will eat its fruits.” Our words should not deceive but instead reveal God’s truth and build up our brothers and sisters in Christ. We should also discern the lies of those who flatter us or make big promises that do not align with biblical standards. In Matthew 10:16, Jesus tells His disciples: “‘Behold, I am sending you out as sheep in the midst of wolves, so be wise as serpents and innocent as doves.’” We can apply this to our lives, being discerning of those who speak to us but not losing our godly innocence either. We should speak truth, but do so in love: “Rather, speaking the truth in love, we are to grow up in every way into him who is the head, into Christ, from whom the whole body, joined and held together by every joint with which it is equipped, when each part is working properly, makes the body grow so that it builds itself up in love” (Ephesians 4:15-16).

understand

Lying is always a sin.
Lies are Satan’s native “language.”
Believers should always speak the truth in love (Ephesians 4:15-16).

reflect

At times, when have you justified telling “white” lies, and what is the problem with this?
How do you speak harsh truths to close friends or family members without alienating them?
How do you discern dishonest flattery from candid compliments?

engage

How can the church ensure that it is speaking the truth in love rather than capitulating to the lies of the culture?
Some believe that lying is acceptable if it serves a good purpose—but Scripture makes it clear that even well-meaning lies are still sin. How can we thoughtfully explain this truth and engage others in meaningful conversation about it?
What are some ways to guard against dishonest flattery?