Answer
“The tongue” is used throughout Scripture in both literal and metaphorical ways, especially in Psalms, Proverbs, and James. The tongue is a “small part of the body” (James 3:5), yet Proverbs 18:21 says it “has the power of life and death.” This holds true whether we’re speaking of spiritual, physical, or emotional “life and death.”
First, we should keep in mind that the word tongue is often a reference to the spoken word. This is a special kind of figure of speech called metonymy, in which one word stands in for another, closely related word. A common example of metonymy is seen in this sentence: “The White House issued a statement.” Of course, the White House, as a building, cannot issue statements; however, in this instance, White House refers to the President, who lives there. In the same way, when Proverbs 15:4 states, “A deceitful tongue crushes the spirit,” tongue is a metonymy. Obviously, a literal, fleshly tongue cannot crush the human spirit, but the words the tongue produces can.
Spiritual:
What our tongue produces has eternal implications, for it reveals what is in our heart. Jesus said that “the good man brings good things out of the good stored up in him, and the evil man brings evil things out of the evil stored up in him” (Matthew 12:35). Isaiah places words on par with actions for displaying a sinful heart (Isaiah 59:2-3). “Men will have to give account on the day of judgment for every careless word they have spoken” (Matthew 12:36). In and of ourselves, we are utterly unable to “tame the tongue” because “it is a restless evil, full of deadly poison” (James 3:8). A tongue under control is a mark of the Spirit’s power. Apart from accepting Jesus’ atonement on the cross, we will be judged according to our words: “For by your words you will be acquitted, and by your words you will be condemned” (Matthew 12:37).
Physical:
In order to take Proverbs 18:21 literally – that the tongue can cause physical life and death – we do not need to tax our imagination. Words create actions, good and bad. A judge or jury, by simply saying a word, can cause a person to be killed or to live. Words often save lives: a doctor advises surgery, a weatherman issues a tornado warning, a counselor gives hope to a suicidal person. Conversely, words can also kill: murders are often initiated because of arguments or verbalized hatred. In the sense of causing action, then, the tongue does indeed have the power of life and death.
Emotional:
Emotions are powerfully affecting, yet they are vulnerable to injury. James describes the tongue as “a fire” (James 3:6) – and who has not been burned by it? Proverbs 15:4 describes a “healing” tongue as “a tree of life.” As much as love is an action, what would romance be without words? Encouragement often comes through spoken words. So does discouragement. “Reckless words pierce like a sword” (Proverbs 12:18). The wound is emotional, and it is deep. What we say can have a profound effect on others.
Conclusion:
God made us expressive beings, so we are nearly lost without communication. That is why we have audio recordings and Braille for the blind, sign language for the deaf, and writing for anyone who has something to say from afar. Indeed, speech has enormous implications, especially as a vehicle for sharing the gospel (Romans 10:14). Therefore, we are commanded to control the tongue, to “keep [it] from evil and your lips from speaking lies” (Psalm 34:13). A Christian’s speech should consistently honor the Lord: with the tongue “we praise our Lord and Father, and with it we curse men, who have been made in God’s likeness. Out of the same mouth come praise and cursing. My brothers, this should not be” (James 3:9-10).
