Question: "What are idle words (Matthew 12:36)?"

Answer: For sure, words are powerful things. God’s words were so powerful that they actually created everything (Genesis 1). But even the words of us humans can do powerful things. Solomon wrote in Proverbs 18:21 that “death and life are in the power of the tongue.” The power of life and death can be seen in jury trials, where witnesses and jury members can speak words that might literally determine whether a defendant lives or dies. Less extreme, but no less real, are the power of encouraging words to give hope and joy and the power of discouraging words to spark dismay and depression.

Jesus said, “I tell you that everyone will have to give account on the day of judgment for every empty word they have spoken” (Matthew 12:36). The KJV translates “every empty word” as “every idle word”; the ESV says, “every careless word.” The Greek phrase is rema argos, meaning “careless or inactive or unprofitable words.” In context, Jesus is contrasting the “good things” within a good person with the “evil things” in the heart of an evil person. We are admonished to make the best use of our words, because words express what is in our hearts: “The mouth speaks what the heart is full of” (Matthew 12:34).

In Matthew 12:37, the significance of words is that they will be used to gauge a person’s spiritual condition in the judgment: “For by your words you will be acquitted, and by your words you will be condemned.” Jesus was speaking to a group of Pharisees who had just accused Jesus of being demon-possessed (verse 24). Jesus calls them a “brood of vipers” and asks them, “How can you who are evil say anything good?” (verse 34). Just as vipers have a mouthful of poison, so the Pharisees had evil words concerning the Savior.

Then Jesus warns the Pharisees of the coming judgment, at which they will be held accountable for their words (Matthew 12:37). There is no better judge of a person’s heart than the words he allows to come forth from his mouth. Just like good trees produce good fruit and bad trees produce bad fruit, so does the mouth reveal the heart’s condition (verse 33).

But it’s not just evil words for which people must give account. Jesus said every “careless” or “idle” word can also be used as a judgment against the speaker. Even the slightest sin, the smallest deviation from God’s perfection, will condemn a person in God’s eyes. The Pharisees’ sin was great—they had blasphemed the Lord of glory with their words—but even seemingly insignificant words, sometimes excused as “slips of the tongue,” are considered sinful if they do not bring glory to God. According to verse 38, Jesus had the last word on this subject, for the scribes and Pharisees changed the subject immediately.

Other passages give additional insight. Ephesians 4:29 sets the standard: “Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen.” James 3:8 advises us on how hard it is to control the tongue: “No human being can tame the tongue. It is a restless evil, full of deadly poison.” Then in James 4:11–12, “Brothers and sisters, do not slander one another. Anyone who speaks against a brother or sister or judges them speaks against the law and judges it. When you judge the law, you are not keeping it, but sitting in judgment on it. There is only one Lawgiver and Judge, the one who is able to save and destroy. But you—who are you to judge your neighbor?”

Given the weighty consequences of our words—even our “careless” ones—we must learn to yield our body’s members, including our tongues, to the control of the Holy Spirit—the only One who can tame the tongue. “Set a guard over my mouth, LORD; keep watch over the door of my lips” (Psalm 141:3).