Matthew Poole and continuators on 1 Peter 3:16

16 Having a good conscience that whereas they speak evil of you, as of evil-doers, they may be ashamed that falsely accuse your good conversation in Christ .

This may be read either, 1. Indicatively, and joined (as by some it is) to the former Verse; and then the sence is, if ye be always ready to answer every one that asketh you a reason of the hope that is in you, ye shall have a good Conscience: Or, rather, 2. Imperatively (which our Translation favours) q. d. not only be ready to make Confession of your Faith; but let your Life and Practice be correspondent to it, in keeping your selves pure from Sin, and exercising your selves unto Godliness, from whence a good Conscience proceeds; here therefore the effect is put for the cause, a good Conscience for a good Life, Act. 23.1.

The sence is, that whereas they speak evil of you, as of evil-doers, your good Conversation may bear Witness for you, confute their Calumnies, and make them ashamed, when it appears that their accusations are false, and that they have nothing to charge upon you but your being followers of Christ.

i. e. That good Conversation, which ye lead as being in Christ; viz. according to his Doctrine and Example, and by the influence of his Spirit.

Marginal references: Chap. 2.12.