Live such good lives among the pagans that, though they accuse you of doing wrong, they may see your good deeds and glorify God on the day he visits us.
There is not much I could add to this verse. Peter is so straight forward here. Many have said that actions speak louder than words, but Peter is saying, 'Let your actions speak so loudly, that even if they accuse you of wrong, in their deepest heart of hearts, they will know that isn't true. They will know that it is an accusation. Then one day they will glorify God because of your loud/godly actions.'