From First and Second Peter, Jude (Coming November 2011) by Daniel Keating, reflecting on 1 Peter 3:15-17:
Peter qualifies how we are to give our explanation to enquirers, urging us to do so with gentleness and reverence. Why these qualities? Probably because Peter expects that non-Christians will often question Christians with an aggressive and even harsh tone (note the term “malign” in the next verse). The world of the first century was generally not friendly toward Christian beliefs and practices. But rather than responding aggressively or even harshly, Christians are to “turn the other cheek” (see Matt 5:39), so to speak, by answering harshness with gentleness, and to do so with reverence for the Lord. Not only does this reflect the spirit of Christ himself; it is also evangelistically effective. The goal is not to proclaim our faith in order to win an argument, but to win others to the faith (3:1) by a gentle and persuasive word.