The following is an excerpt from The MacArthur New Testament Commentary on 2 Corinthians 10.

For the weapons of our warfare are not of the flesh, but divinely powerful for the destruction of fortresses. We are destroying speculations and every lofty thing raised up against the knowledge of God, and we are taking every thought captive to the obedience of Christ, (2 Corinthians 10:4–5)

To successfully fight the spiritual war requires weapons from the heavenly arsenal. Only those divinely powerful weapons are suited for the destruction of the enemies’ fortresses. That term would convey to the New Testament reader the thought of a formidable stronghold. Corinth, like most major cities in Greece, had an acropolis. Located on a mountain near the city, the acropolis was a fortified place into which the inhabitants could retreat when attacked. Ochuroma (fortresses) was also used in extrabiblical Greek to refer to a prison. People under siege in a fortress were imprisoned there by the attacking forces. The word was also used to refer to a tomb.

Fleshly weapons cannot successfully assault the formidable strongholds in which sinners have entrenched themselves. Such impotent weapons cannot bring about the destruction of those fortresses, which Paul defined specifically as speculations (logismos), a general word referring to any and all human or demonic thoughts, opinions, reasonings, philosophies, theories, psychologies, perspectives, viewpoints, and religions. The fortresses in view here are not demons, but ideologies. The notion that spiritual warfare involves direct confrontation with demons is foreign to Scripture. Christians who verbally confront demons waste energy and demonstrate ignorance of the real war. We are not called to convert demons, but sinners. The battle is rather with the false ideologies men and demons propagate so that the world believes them. Doomed souls are inside their fortresses of ideas, which become their prisons and eventually their tombs—unless they are delivered from them by belief in the truth.

Paul further defined sinners’ strongholds of ideas as every lofty thing—that is, any unbiblical system of thought exalted as truth—that is raised up against the knowledge of God. There is the key. Spiritual warfare is not a battle with demons. It is a battle for the minds of people who are captive to lies that are exalted in opposition to Scripture. In 1 Corinthians 3:20, he called them the useless reasonings of the worldly wise —all the anti-biblical ideologies, false religions, and pseudo gospels spawned by Satan. Paul knew those fortresses well, having lived his entire life before his conversion in one of them. He was a zealous follower of the Judaism of his day, which had turned from its Old Testament roots and become a ritualistic system of works-righteousness.

Like Paul, before salvation, all unbelievers have a fortress in which they attempt to hide from the true knowledge of God. Those fortresses take endless forms in philosophy, psychology, world religions, cults, apostate forms of Christianity, or evolutionary naturalism—a predominant fortress in Western culture today.

The objective of our warfare is to change how people think— taking every thought they have and making it no longer captive to a damning ideology, but captive to the obedience of Christ. To do so, the proper weapon is necessary. To assault and throw down the fortresses of false religions, opinions, beliefs, and philosophies, only one weapon will suffice: the truth. That is so obvious that Paul does not mention it. Only one thing exposes and corrects lies—the truth. Thus, the only offensive weapon in the Christian soldier’s armor is “the sword of the Spirit, which is the word of God” (Eph. 6:17). Spiritual warfare is an ideological conflict, fought in the mind by assaulting the proud fortresses of ideas that sinners erect against the truth. Aichmalotizo (taking captive) literally means, “to take captive with a spear.” Using God’s truth, believers smash enemy fortresses to the ground, march the prisoners out, and bring them into subjection (obedience) to the Lord Jesus Christ. They rescue sinners from the domain of darkness, “snatching them out of the fire” (Jude 23). After being taken prisoner by Jesus Christ on the Damascus Road, Paul immediately asked, “What shall I do, Lord?” (Acts 22:10). The rebellion of his sinful, proud heart was ended; the walls of his fortress crashed down in ruin, and the Lord Jesus Christ conquered his heart. Such is the experience of all the redeemed; the term the obedience of Christ is a synonym for salvation (cf. Acts 6:7; Rom. 1:5; 15:18; 16:26; Heb. 5:9).