Jamieson, Fausset and Brown on 1 Peter 2:15

15. Ground of his directing them to submit themselves (1Pe 2:13).

put to silence--literally, "to muzzle," "to stop the mouth."

ignorance--spiritual not having "the knowledge of God," and therefore ignorant of the children of God, and misconstruing their acts; influenced by mere appearances, and ever ready to open their mouths, rather than their eyes and ears. Their ignorance should move the believer's pity, not his anger. They judge of things which they are incapable of judging through unbelief (compare 1Pe 2:12). Maintain such a walk that they shall have no charge against you, except touching your faith; and so their minds shall be favorably disposed towards Christianity.