2 Corinthians 10:4-5, 10

(for the weapons of our warfare are not of the flesh, but mighty before God to the casting down of strongholds); casting down imaginations, and every high thing that is exalted against the knowledge of God, and bringing every thought into captivity to the obedience of Christ

For, His letters, they say, are weighty and strong; but his bodily presence is weak, and his speech of no account.