Commentaries:
This verse is a little vague in the last phrase. What do you love, death or life? The one that we love we will eat the fruit of. Will we eat the fruit of death? Or will we eat the fruit of life?
Anybody's words are spirit; Jesus is not the only one whose words are spirit (John 6:63). The difference between us and Him is that His words are always life. His words are always abundant, eternal, or everlasting life. They surcharge the air to move us, our hearts, our minds, our spirits in the direction that they are moving. If we would yield to them, we can be carried along by them all the way into the Kingdom of God. This is why there is life in them!
Unfortunately, the same cannot be said of any of us—that our words are life—because often times our words carry death with them. They do not go forth in the best of attitudes, backed with a unclear understanding of what is really going on, and all too often we speak far too hastily and emotionally.
What the Bible calls "spirit" can be communicated. It is almost as if it surcharges the environment. The words and the disposition or environment in which they are delivered and received are important to its communication. How many times have we said something to somebody who became confused, upset, angry, or frustrated at what we said, and we had to apologize or explain further by saying, "Well, that's not what I meant"? Yet, that was how the receiver heard it. Things were communicated that to the recipient colored what was sent. Communication is a terribly difficult aspect of life.
John W. Ritenbaugh
The Holy Spirit and the Trinity (Part Four)
Other Forerunner Commentary entries containing Proverbs 18:21:
Deuteronomy 8:3
Matthew 4:4
Luke 15:25-30
James 3:5-6