It is written:
“People who don’t believe are living all around you. They may say that you are doing wrong. So live such good lives that they will see the good you do, and they will give glory to God on the day he comes.” (1 Peter 2:12)
Here, Peter tells Christians that they need to try and live good lives. One of the reasons will hopefully be that they will “give glory to God on the day He comes.”
What does this mean?
Throughout the Bible, the phrase “glorifying God” was used to have reference to conversion of man from sin.
Acts 13:48-Now when the Gentiles heard this, they were glad and glorified the word of the Lord. And as many as had been appointed to eternal life believed.
Romans 15:9-and that the Gentiles might glorify God for His mercy, as it is written: “FOR THIS REASON I WILL CONFESS TO YOU AMONG THE GENTILES, AND SING TO YOUR NAME.”
2 Thessalonians 3:1-Finally, brethren, pray for us, that the word of the Lord may run swiftly and be glorified, just as it is with you,
Revelation 5:13-And every creature which is in heaven and on the earth and under the earth and such as are in the sea, and all that are in them, I heard saying: “Blessing and honor and glory and power Be to Him who sits on the throne, And to the Lamb, forever and ever!”
The Greek of this passage in 1 Peter suggests that this is, indeed, what the Apostle has in mind:
“We see the same contrast in Revelation between those who believe and glorify God (Rev 11:13) and those who refuse to repent and do not honor him (Rev 16:9). Peter exhorted believers to live noble lives because in doing so unbelievers will see their good works. Because they observe such works, some unbelievers will repent and believe and therefore give glory to God on the last day.28 The use of the participle “see” (from the verb epopteu) also suggests that salvation is in view, for the same term is used in 1 Pet 3:2, where the submission of wives is intended to lead to the salvation of unbelieving husbands. Peter was confident that some unbelievers will be saved when they notice the godliness of believers. The unbelievers may revile Christians, but as they notice the goodness in their lives, some will repent and be saved, and as a result of their salvation God will be glorified.” (Thomas R. Schreiner, The New American Commentary: 1, 2 Peter, Jude, Volume 37, 124 (Kindle Edition); Nashville, TN; B&H Publishing Group)
While Christians are not sinless (1 John 1:7-9; 2:1-2), we are called upon to live lives that will help others to see Christ living in us.
If a non-Christian looks at your life, could he tell that you are a Christian?