Eyewitnesses

[1 Peter 2:12] Having your conversation honest among the Gentiles: that, whereas they speak against you as evildoers, they may by your good works, which they shall behold, glorify G-d in the day of visitation.
[15] For so is the will of G-d, that with well doing ye may put to silence the ignorance of foolish men:
A good walk does not make us pious, but we must first be pious and believe before we attempt to lead a good course. Faith first receives from G-d, and then love given to our neighbors who are watching our every move.
They by whom you are surrounded, and who will certainly observe your conduct, they shall be eyewitnesses and shall behold on close inspection; as opposed to their ignorance of the true character of Believers, maybe judging you on mere hearsay or appearances. This kind of godly living makes our conduct honorable among those who don't know G-d yet. Though you can expect that they will speak against you as evildoers, they can still be brought to glorify G-d by seeing your godly conduct.
Neighbors form a high estimate of the G-d whom Believers worship, from the exemplary conduct of Believers themselves. We must do well in all things, not with a view to our own glory, but to the glory of G-d.
Put to silence of one’s neighbors is literally, to muzzle, to stop the mouth. Their ignorance is spiritual not having the knowledge of G-d, and therefore ignorant of the children of G-d, and misconstruing their acts, influenced by mere appearances, and ever ready to open their mouths, rather than their eyes and ears. Their ignorance should move the believer's pity, not his anger. They judge of things which they are incapable of judging through unbelief.
One needs to maintain such a living and walk that they shall have no charge against you, except touching your faith; and so their minds shall be favorably inclined towards Christianity. One of the best ways of meeting the accusations of our enemies is to lead a life of strict integrity. It is not easy for the wicked to reply to this argument.
That by doing good you may put to silence the ignorance of foolish men: Peter knows that our conduct is a way to defend the gospel. He knows that those who never read the Bible will read our lives, so it is by doing good that we put to silence the ignorance of foolish men.
Honor all people, love the brotherhood and fear G-d.