Why should we let no unwholesome talk come out of our mouths (Ephesians 4:29)?

TL;DR:

Ephesians 4:29 warns believers to avoid coarse language. This and other scriptures teach that words should be chosen with care, as they are part of a believer’s witness for Christ.

Ephesians 4:29 exhorts believers to guard our words so that what we say edifies and encourages others. The book of Ephesians explains the doctrine of grace and the changed life that all believers have been called into as children of God. Chapter four presents practical applications of that reality, including the significance of our words. Besides Ephesians, many other scriptures discuss the consequences that can come from how we communicate with others. The wisdom books, Proverbs and Ecclesiastes, advise readers to choose our words carefully (Proverbs 4:24; 10:19; 13:3; 15:4; Ecclesiastes 5:2; 10:12). The New Testament also discusses how what we say has the power to damage or edify. Jesus often discussed the positive example believers should show to the world (Matthew 5:13; 7:16–20; Mark 4:21–22; Luke 11:33–36), including what we say (Luke 6:45; Matthew 12:36–37). The impact our words have on our testimony is expressed in other New Testament passages as well (Colossians 4:5–6; James 3:5–6; Titus 2:7–8; 1 Peter 3:10–11). In short, the Bible teaches that our words matter.

from the old testament

In Psalm 141:3, David pleads with the Lord, “Set a guard, O LORD, over my mouth; keep watch over the door of my lips!” Believers who have trouble reigning in their words would be wise to pray this as well. As children of God, we should be mindful of not allowing our words to diminish our witness.
David’s son, Solomon, echoes the message from that Psalm in the instruction he gives to his own son in Proverbs 4:24: “Keep your mouth free of perversity; keep corrupt talk far from your lips” (NIV). This is sage advice from one of the wisest men who ever lived.

from the new testament

In Ephesians 4:29, Paul advises believers, “Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear.” Paul devotes chapter four to instructing the Ephesians “to walk in a manner worthy of the calling to which you have been called” (v. 1), which involves what we say. Our words can either tear down or build up, ruin our witness or glorify our Creator.
In Matthew 12:36, Jesus’s reproach of the Pharisees emphasizes the significance of words: “But I tell you that everyone will have to give account on the day of judgment for every empty word they have spoken” (NIV). The Pharisees had just accused Jesus of being demon-possessed after seeing Him expel a demon from a man. But that message isn’t meant just for the Pharisees; Jesus says “everyone,” which is a reminder to all believers that our words matter. This doesn’t mean our words will never offend others; speaking the truth will often offend unbelievers (2 Corinthians 2:15–16). But telling the truth is not the same as unwholesome talk.
Colossians 4:5–6 advises believers to “Walk in wisdom toward outsiders, making the best use of the time. Let your speech always be gracious, seasoned with salt, so that you may know how you ought to answer each person.” Believers are supposed to be “the salt of the earth” (Matthew 5:13), an example to others. Our words are a vital part of our witness.

implications for today

Have you seen the bumper sticker that says, “If you don’t have something nice to say. . .call me—we’ll have coffee”? Of course, the last part isn’t how the saying usually ends, but the twist implies there’s something fun in dishing dirt about others. That shouldn’t be the type of “fun” believers engage in, though. Our Lord has instructed us, “as you wish that others would do to you, do so to them” (Luke 6:30–31). If we would be hurt by gossip about us, we shouldn’t engage in gossip about others. But the problem isn’t just talking unkindly about other believers. Our words are a big part of our witness to the world. What are our neighbors, friends, and coworkers to think when we curse or tell bawdy jokes? Why would people accept your invitation to church if they can’t distinguish your words and actions from the world’s? What are you offering that they don’t already have? Our words should glorify our Father in heaven. Before you speak, think of this: If Jesus were standing beside you, would you be comfortable telling that off-color joke or slipping in that coarse language? If the answer is “no,” then you should edit your speech because Jesus is always with us. We should strive to build up others with our words, while still being truthful. The Bible teaches that our words matter.

understand

Ephesians 4:29 urges speech that edifies others.
The Bible emphasizes the importance of avoiding corrupt talk.
Our speech impacts how others perceive Christ through us.

reflect

How do you ensure that your words reflect Christ's love and grace in your daily conversations?
Are there areas in your speech where you struggle with unwholesome talk, and how can you address those challenges?
How can you apply Ephesians 4:29 to encourage and build up others in your relationships?

engage

How does the way we speak impact the way non-believers view Christ and the church?
What are some practical ways to guard our speech and ensure it glorifies God in every situation?
How can we balance speaking truth in love without falling into the trap of unwholesome talk or gossip?