A.T. Robertson Commentary 1 Peter 2:15

"For so is the will of God, that by well-doing ye should put to silence the ignorance of foolish men:" — 1 Peter 2:15 (ASV)

By well-doing (αγαθοποιουντας). Present active participle of αγαθοποιεω, only in LXX and N.T. . In accusative case agreeing with υμας understood, accusative of general reference with φιμοιν, present active infinitive (epexegetic infinitive after το θελημα του θεου, the will of God), late and rare verb (from φιμος muzzle), as in Mt 22:12.

The ignorance of foolish men (την των αφρονων ανθρωπων αγνωσιαν). Αγνωσια is late and rare word (in the papyri) from alpha privative and γνωσις (knowledge), in N.T. only here and 1 Corinthians 15:24 (disgraceful ignorance in both instances). Note alliteration.