A.T. Robertson Commentary 1 Peter 3:16

"having a good conscience; that, wherein ye are spoken against, they may be put to shame who revile your good manner of life in Christ." — 1 Peter 3:16 (ASV)

Having a good conscience (συνειδησιν εχοντες αγαθην). Present active participle of εχω. See 2:18 for συνειδησιν and 3:21 for συνειδησις αγαθη again ("a quasi-personification," Hart).

That they may be put to shame (ινα καταισχυνθωσιν). Purpose clause with ινα and the first aorist passive subjunctive of καταισχυνω, old verb, to put to shame (Luke 13:17; 1 Peter 2:6).

Wherein ye are spoken against (εν ω καταλαλεισθε). Present passive indicative of καταλαλεω, for which see 2:12 with εν ω also. Peter may be recalling (Hart) his own experience at Pentecost when the Jews first scoffed and others were cut to the heart (Acts 2:13,37).

Who revile (ο επηρεαζοντες). Articular present active participle of επηρεαζω, old verb (from επηρεια, spiteful abuse), to insult, in N.T. only here and Lu 6:28.

In Christ (εν Χριστω). Paul's common mystical phrase that Peter has three times (here, 5:10,14), not in John, though the idea is constantly in John. Peter here gives a new turn (cf. 2:12) to αναστροφη (manner of life). "Constantly the apostle repeats his phrases with new significance and in a new light" (Bigg).