John Calvin on 1 Peter 3:16

Having a good conscience What we say without a corresponding life has but little weight; hence he joins to confession a good conscience. For we see that many are sufficiently ready with their tongue, and prate much, very freely, and yet with no fruit, because the life does not correspond. Besides, the integrity of conscience alone is that which gives us confidence in speaking as we ought; for they who prattle much about the gospel, and whose dissolute life is a proof of their impiety, not only make themselves objects of ridicule, but also expose the truth itself to the slanders of the ungodly. For why did he before bid us to be ready to defend the faith, should any one require from us a reason for it, except that it is our duty to vindicate the truth of God against those false suspicions which the ignorant entertain respecting it. But the defense of the tongue will avail but little, except the life corresponds with it.

He therefore says, that they may be ashamed, who blame your good conversation in Christ, and who speak against you as evil-doers; as though he had said, “If your adversaries have nothing to allege against you, except that you follow Christ, they will at length be ashamed of their malicious wickedness, or at least, your innocence will be sufficient to confute them.”

1 Peter 3:17-18

17. For it is better, if the will of God be so, that ye suffer for well doing, than for evil doing.

17. Praestat enim benefaciendo (si ita fert voluntas Dei) pati quàm malefaciendo:

18. For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit:

18. Quia et Christus semel pro peccatis passus est, justus pro injustis, ut nos adduceret Deo; mortificatus quidem carne, vivificatus autem spiritu.