Good preaching is both instructive and destructive. It instructs us in the ways and words of God. But it also destroys - sinful strongholds, faulty arguments, and every lofty opinion raised against the knowledge of God.
As the apostle Paul reminds us, "For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ" (2 Corinthians 10:4-5).
And as Proverbs 21:22 tells us, "A wise man scales the city of the mighty and brings down the stronghold in which they trust."
Preachers, in what strongholds are your people trusting? In what arguments have they erroneously believed? Your preaching - your faithful, expositional, Christ-exalting, Spirit-empowered preaching - is the God-ordained means of destroying those strongholds.