The Lord frequently uses comparison and contrast to provide insight for discovering biblical definitions. For instance, our text verse contrasts the carnal with the spiritual. This truth is not limited to our text as 1 Corinthians 3:1 also sets forth this teaching and contrast. In a related study, the Bible repeatedly contrasts the spirit and flesh (Isaiah 31:3; Matthew 26:41; John 3:6; John 6:63; Galatians 5:17). By considering these truths together, we find that the Lord defined a “carnal mind” (Romans 8:7) as someone who is “in the flesh” (Romans 8:8). Based upon these verses and others, we understand the word carnal to mean that which is earthly, natural, or fleshly.
The Bible says that “out of the abundance of the heart the mouth speaketh” (Matthew 12:34). This means that the words proceeding out of our mouths originate in our hearts. When we speak bitter words, it is because there is bitterness within our hearts. David likened bitter words to arrows that pierce the flesh (Psalm 64:3). Our words ought to be “seasoned with salt” (Colossians 4:6); instead, we often allow our words to pierce through others. We tear people down rather than building them up. Why is this? Because we have a root of bitterness growing inside that finds its way from our hearts into and out of our mouths. Those who demean others generally do so because they are bitter. Attempts to justify this behaviour are fruitless because the Lord knows the root of the problem stems from our heart.