16 keeping a clear conscience, so that those who speak maliciously against your good behavior in Christ may be ashamed of their slander.

Read 1 Peter 3:16 Using Other Translations

Having a good conscience; that, whereas they speak evil of you, as of evildoers, they may be ashamed that falsely accuse your good conversation in Christ.
having a good conscience, so that, when you are slandered, those who revile your good behavior in Christ may be put to shame.
But do this in a gentle and respectful way. Keep your conscience clear. Then if people speak against you, they will be ashamed when they see what a good life you live because you belong to Christ.