“Casting down imaginations” appears in 2 Corinthians 10, which provides a defense of Paul’s ministry as he is interacting with others in person and through letter (see verses 7–11). In the middle of Paul’s argument for the weapons of warfare that he utilizes in his ministry is 2 Corinthians 10:5, “Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ” (KJV). Paul is utilizing divine weapons, not weapons according to human standard or the flesh.
Some in Corinth had accused Paul of walking according to the flesh (2 Corinthians 10:2). To walk according to the flesh is to live independently of God and in hostility to Him (Romans 8:5–8). Paul tells us that living according to the flesh must be eliminated, as it leads to death (Romans 8:12). We should live in dependence on God, yielding to His Spirit, resulting in obedience to Him (Romans 8:13). With Paul’s teaching on the sinfulness of living according to the flesh, the magnitude of the accusation against Paul becomes apparent. For this reason, Paul takes time in 2 Corinthians to defend himself against such an accusation.
Paul tells the Corinthians the war he fights is being waged with divine power (2 Corinthians 10:3–4) and weapons of divine origin—these are not fleshly weapons. The war he is discussing is a war of the mind. In just verses 4–5, Paul addresses speculations (or imaginations or pretensions), the knowledge of God, and thoughts, all of which occur in the mind. Paul’s actions in this war are casting down imaginations, taking thoughts captive, destroying systems of sophistry raised against God, and demolishing arrogant philosophies contrary to the knowledge of God. All of these things involve the mind. It seems clear that Paul is describing a war of the mind.
The Greek words translated “casting down imaginations” in the KJV can also be translated as “destroying arguments” (ESV) or “destroying speculations” (NASB 1995). These latter translations add some clarity to the meaning of the phrase. Paul is utilizing divine weapons to destroy or bring down speculations, arguments, and reasonings that are against the knowledge of God.
The knowledge of God is that which He has revealed about Himself throughout the Scriptures (Hosea 4:1; Romans 11:33) and is contrary to the imaginations or speculations Paul is discussing. This knowledge is passed to others through the Scriptures (Proverbs 2:6; 2 Timothy 3:16–17) and through those who live according to the Scriptures (2 Corinthians 2:14). Understanding God’s will, as revealed in the Scriptures, leads to a knowledge of Him (Colossians 1:9–10). As the Scriptures are better understood, the mind is renewed, and the Christian is transformed (Romans 12:1–2). This principle leads to the destruction of strongholds or fortresses of thought as the Bible is the divine weapon (Ephesians 6:17).
The reasoning of this world is opposed to the truth of God. The unbelieving mind clings to what it considers logic and rock-solid arguments to fend off any impingement of God’s truth into their lies. But when a person is born again, he or she admits the folly of the old way of thinking and discovers Christ to be the wisdom of God (1 Corinthians 1:24). Let us then study the Scriptures (2 Timothy 2:15), understand God’s will, and attain the knowledge of God. Then we can cast down imaginations that are contrary to the knowledge of God. We can maintain freedom from the empty philosophies of man and remain loyal to the philosophy of Christ (Colossians 2:8), walking according to the Spirit (Romans 8:5). The war of the mind is being waged, and Paul has revealed proper actions to take.