Paul commands us to think about what he says. Use your mind. Engage your reasoning powers when you hear the Word of God. In another place, Jesus warned what happens if we don’t and what blessing may come if we do. He told a parable about four soils (Matt. 13:3–9). When the seed of the Word is sown on the first three, it bears no fruit. Only the fourth soil bears fruit. What’s the difference?
We get a glimpse of the problem when we compare the first and fourth soils. Jesus said concerning the seed sown on the first soil, the path: “When anyone hears the word of the kingdom and does not understand it, the evil one comes and snatches away what has been sown in his heart.” Jesus focuses on the failure to understand. Not understanding the Word results in the Word being snatched away. Therefore, understanding with the mind is not optional. It’s crucial to conversion and fruit-bearing. Our lives hang on it. Then concern- ing the seed sown on the fourth soil, the good soil, he says, “This is the one who hears the word and understands it. He indeed bears fruit and yields, in one case a hundredfold, in another sixty, and in another thirty” (Matt. 13:23). The difference between the soil that is lifeless and the soil that bears fruit is understanding.
It is true, as Paul says in Romans 10:17, that “faith comes from hearing, and hearing through the word of Christ.” So hearing is important. But Jesus says that hearing without understanding produces nothing. When we hear the Word of God, Paul says, we must “think over” what we hear. Otherwise, we will fall under the indictment of Jesus: “Hearing they do not hear, nor do they understand” (Matt. 13:13).
So, even though our natural minds are depraved and darkened and foolish, the New Testament demands that we use them in coming to faith and leading people to faith and in the process of Christian growth and obedience. There is no way to awaken faith or strengthen faith that evades thinking.- John Piper, Think: The Life of the Mind and the Love of God, p. 61, 62