The first chapter and a half of 1 Peter focuses on several key principles of the Christian life which serve as an important foundation for everything else in that epistle: we are saved and secured by the power of God, because we are saved we are no longer citizens of this earth but rather of heaven, therefore we should not become attached to the things of this earth, but we should live so as to reflect the nature of the God that saved us. By the time you get to 1 Peter 2:11-12, the author has hammered these principles out in a way that is hard to forget, but them he wraps it all up in verse 12 by saying that the whole purpose is so that when people (unbelievers) look at a believer's life, they will end up giving God glory. Not that all unbelievers will be saved, but all will ultimately glorify God, whether they become believers themselves, or whether they go into eternal judgment acknowledging the mercy and goodness of God that they rejected. The question that each of us must answer is whether people watching our lives as believers see God in us or just another good person.