Prayer Principle 3A: 
Submission Introduction 6

Among the Gentiles. The heathen by whom you are surrounded, and who will certainly observe your conduct. See Barnes "1Th 4:12", "That ye may walk honestly towards them that are without." Comp. #Ro 13:13.

That, whereas they speak against you as evil doers, . Marg., wherein. Gr., Greek-- in what; either referring to time, and meaning that at the very time when they speak against you in this manner they may be silenced by seeing your upright lives; or meaning in respect to which--that is, that in respect to the very matters for which they reproach you they may see by your meek and upright conduct that there is really no ground for reproach. Wetstein adopts the former, but the question which is meant is not very important. Bloomfield supposes it to mean inasmuch, whereas. The sentiment is a correct one, whichever interpretation is adopted It should be true that at the very time when the enemies of religion reproach us, they should see that we are actuated by Christian principles, and that in the very matter for which we are reproached we are conscientious and honest.

They may, by your good works, which they shall behold. Gr., "which they shall closely or narrowly inspect." The meaning is, that upon a close and narrow examination, they may see that you are actuated by upright principles, and ultimately be disposed to do you justice. It is to be remembered that the heathen were very little acquainted with the nature of Christianity; and it is known that in the early ages they charged on Christians the most abominable vices, and even accused them of practices at which human nature revolts. The meaning of Peter is, that while they charged these things on Christians, whether from ignorance or malice, they ought so to live as that a more full acquaintance with them, and a closer inspection of their conduct, would disarm their prejudices, and show that their charges were entirely unfounded. The truth taught here is, that our conduct as Christians should be such as to bear the strictest scrutiny; such that the closest examination will lead our enemies to the conviction; that we are upright and honest. This may be done by every Christian; this his religion solemnly requires him to do.

Glorify God. Honour God; that is, that they may be convinced by your conduct of the pure and holy nature of that religion which he has revealed, and be led also to love and worship him. See Barnes "Mt 5:16".

In the day of visitation. Many different opinions have been entertained of the meaning of this phrase, some referring it to the day of judgment; some to times of persecution; some to the destruction of Jerusalem; and some to the time when the gospel was preached among the Gentiles, as a period when God visited them with mercy. The word visitation (Greek,) means the act of visiting or being visited for any purpose, usually with the notion of inspecting conduct, of inflicting punishment, or of conferring favours. Comp. #Mt 25:36,43 Lu 1:68,78 7:16 19:44. In the sense of visiting for the purpose of punishing, the word is often used in the Septuagint for the Heb. Hebrew, (pakad,) though there is no instance in which the word is so used in the New Testament, unless it be in the verse before us. The "visitation" here referred to is undoubtedly that of God; and the reference is to some time when he would make a "visitation" to men for some purpose, and when the fact that the Gentiles had narrowly inspected the conduct of Christians would lead them to honour him. The only question is, to what visitation of that kind the apostle referred. The prevailing use of the word in the New Testament would seem to lead us to suppose that the "visitation" referred to was designed to confer favours rather than to inflict punishment, and indeed the word seems to have somewhat of a technical character, and to have been familiarly used by Christians to denote God's coming to men to bless them; to pour out his Spirit upon them; to revive religion. This seems to me to be its meaning here; and, if so, the sense is, that when God appeared among men to accompany the preaching of the gospel with saving power, the result of the observed conduct of Christians would be to lead those around them to honour him by giving up their hearts to him; that is, their consistent lives would be the means of the revival and extension of true religion.

And is it not always so? Is not the pure and holy walk of Christians an occasion of his bending his footsteps down to earth to bless dying sinners, and to scatter spiritual blessings with a liberal hand? Comp. See Barnes "1Co 14:24", See Barnes "1Co 14:25".

{1} "whereas" "wherein"

{e} "good works" #Mt 5:16