2Corinthians 10:3-6 For though we walk in the flesh, we do not war after the flesh: (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;) Casting down imaginations, and every high thing that exalts itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ; And having in a readiness to revenge all disobedience, when your obedience is fulfilled.
‘For though we walk in the flesh, we do not war after the flesh.’ Here Paul denies the charges of 2Corinthians 10:1-2. Though he lived in the flesh he did not war after the flesh (10:3-5). His weapons were not carnal (10:4-5; Eph. 6:10-18; 1Tim. 1:18; 2Tim. 2:3-5; Rom. 13:12).
‘But mighty through God to the pulling down of strong holds.’ Four great conquests of spiritual weapons:  Destruction of strongholds – we destroy reasonings of pagan philosophers and Jewish rabbis and their dogmas that nullify the Word of God and the facts of the Gospel. These fortifications we pull down and demolish. We put to flight the demon powers and alien armies, raising the banner of the cross high on the field of battle (10:4). Destroying all ideas or opinions about ourselves, others and God that is in contrast with His Word on these matters.  Casting down imaginations – we demolish all theories, reasonings, and any high system of ethics, religion, mythology, metaphysics, sublime doctrines or philosophy set forth to defy the knowledge of God (10:5). All the boasted gods, lords, sacrificial and mediatorial systems fell before the Gospel. The high-sounding phrases of Plato, Aristotle, the Stoics, church doctrines and even Judaism fell before the preaching of the crucified and risen Christ. Heathenism shrank before the Gospel and called on secular powers to defend it.  Bringing into captivity every thought to the obedience of Christ – we take every thought prisoner and lead it into captivity to obey Christ (10:5). Lascivious, vain and evil thoughts of all kinds are brought down and made obedient to His laws. That includes any thinking which is contrary to virtue, purity and righteousness. We cannot allow any unholy thoughts (standard set in Philippians 4:8) to come into our minds and defile us. See Matthew 15:19; Mark 7:21-22; 1Corinthians 13:5; Galatians 5:19; Philippians 4:8; Genesis 6:5; Proverbs 15:26; Isaiah 55:7; 59:7 and Jeremiah 4:14.  Having in readiness to avenge all disobedience – we stand at all times ready, so to speak, to court-martial any opposing the Gospel of Christ, after separating ourselves from them (10:6). The whole picture here is that of a strongly fortified city where the enemy makes his last stand; entrenching himself about the walls; raising towers and preparing engines of defence and offence upon the walls to ensure victory. The fortifications, walls, towers, and castles are taken by the Gospel and the whole opposition is destroyed and taken captive. We have no excuse for sinful thoughts; we are to wear the helmet of salvation (Eph. 6:17) a state of repentance, which mean to renew our minds (Rom. 12:2; Eph. 4:23) so that God’s mind and thoughts (as given in His Word) can become ours.