"For though we walk in the flesh, we do not war after the flesh." (2 Corinthians 10:3)
This verse introduces a famous apologetic charge to the saints. The key to the whole passage is the qualifier "we do not war after the flesh."
We must conduct war with non-flesh weapons, since "we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places" (Ephesians 6:12). Fleshly wisdom (2 Corinthians 1:12) often is nothing more than a "snare of the devil" (2 Timothy 2:26) and may well spoil us if we are not very careful (Colossians 2:8).
The objective, of course, is to bring every intellectual argument captive to the truth of Scripture. This is done by the pulling down of strongholds and "casting down imaginations, and every high thing that exalteth itself against the knowledge of God" (2 Corinthians 10:5). This warfare, if not done according to the flesh (2 Corinthians 1:17), is "mighty through God" (2 Corinthians 10:4).
Nowhere in these verses is there permission or an implied need to learn the thoughts of the enemy before we can bring them into captivity. Biblical data insist that the flesh has "no good thing" (Romans 7:18) and cannot understand the things of God. The weapons we have are not fleshly (i.e., natural thinking, natural emotion, human reasoning, etc.). Our weapons (Ephesians 6) are the "sword of the Spirit" (offensive) and the "shield of faith" (defensive), and we’re protected by the full armor of God—praying always. It is not possible to learn all the subtle arguments of the enemy. What is possible, however, is a knowledge of the truth through our having the "mind of Christ" (1 Corinthians 2:16) that will make us sufficient for "all things that pertain unto life and godliness" (2 Peter 1:3). HMM III