NOTES for 1P 3:15
Without claiming to unfold the whole meaning contained in this phrase of Peter, several points can be noted. What does it mean to "sanctify God in the heart"? It means, perhaps, to hold with all one's strength faith in God's holiness, in His ultimate, absolute goodness. From this faith then follows the desire to glorify God, thank Him, and worship Him.
God's goodness is also the source of all our hope, our trust. An account of our hope, then, is our testimony to His goodness, His love, and therefore to Christ, His death and resurrection.
Such testimony is commanded to us by the Lord in His "Great Commission": to go into all the world and preach the Gospel to every creature, to go and teach all nations. We know how to shield ourselves from this commission, for example with Jesus' words: "Do not cast pearls before swine" (cf. Matt. 7:6), silently implying that everyone with whom we do not want to speak is swine. The apostle Peter calls us to crawl out of hiding and give an account to "everyone."
The words "with meekness and reverence" are remarkable. Reverence is understandable, since we must speak of God's holiness. Foolish jokes and comparisons are clearly out of place here, although our word should be convincing, "with salt," as the apostle Paul says. And meekness means that we must not force our listeners to accept our testimony or teach them from above. We can share with them our experience, the experience of the Church, but we have no right to encroach on their freedom to make a decision.