Romans 12:17-18 — Recompense to no man evil for evil. Provide things honest in the sight of all men.
If it be possible, as much as lieth in you, live peaceably with all men.
recompense = render
evil for evil — on no occasion is a believer to retaliate. The stress is on "no man." There is also stress on "all men."
Matthew 5:43-48 — Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; that ye may be the children of your Father which is in heaven: for He maketh His sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust. For if ye love them which love you, what reward have ye? do not even the publicans the same? And if ye salute your brethren only, what do ye more than others? do not even the publicans so? Be ye therefore perfect, even as your Father which is in heaven is perfect.
1 Thessalonians 5:15 — See that none render evil for evil unto any man; but ever follow that which is good, both among yourselves, and to all men.
By avoiding retaliation, we avoid justifiable suspicion and criticism
The message in verse 18 is "see that it isn't you who breaks the peace."
honest = honorable, beautiful. Providing for honest things, not only in the sight of the Lord, but also in the sight of men (2 Corinthians 8:21).
Don't just do right period. Do right and think of how it appears to others.
The second phrase [of verse 18] talks about you: "As much as in you lies" — the emphasis on you — "live at peace with all men." That does not mean peace at the expense of righteousness, but the point is this: you are never to be the one to break the peace. If the other fellow breaks it, even then you are to do all you can to keep the peace. When the peace is broken, don't look at the other fellow, but look at yourself and see if you have done all you can do.
We are not to use this exhortation for simply giving in to everything that comes. For instance, when it concerns me individually, then it is right for me to give, give, give to the last drop, and never break the peace! But I also have a duty to others in my life, and when, by permitting somebody to run over me, I fail in my duties to others, then that is a different matter. — Alva J. McClain, Romans: The Gospel of God's Grace, page 215.