2 Corinthians 10:4-5, 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

For they say, “His letters are weighty and strong, but his personal presence is unimpressive and his speech contemptible.”