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. See that none render evil for evil unto any man; but ever follow that which is good, both among yourselves, and to all men.
The command is to watch that no one pays back evil with evil to any person, but to always chase after what is good both among fellow believers and toward all people. It is a duty to be obeyed most earnestly and lived out in life, bound up with drawing near to God and with fearing to sin against Him by injustice toward brethren. That fear means fearing to offend God's children and refusing to wound or bruise His heritage, while showing the most tender interest for every one for whom Christ died and hoping in His mercy for sinners.
It forbids handling a brother's reputation in a way that offends God when one's own ideas are not exalted and honored as thought deserved, because God loves those brethren as He loves us and takes as much pleasure in them as in us. It calls for cultivating kindness and forbearance and love and for representing Christ in character, leaving no place for evil speaking and accusing and faultfinding and misrepresenting brethren because one's own individual ideas are not treated as of highest value. Conduct shows what a person's influence and principles are worth, for if self is the center self will be seen in all that is done, while if Christ is the center His likeness will be borne.
This pursued goodness is visible, letting light shine so that others see something in the life. It calls believers to hold closely together in love and to stay true to one another and to God, never retaliating but always pursuing the good. This united love and goodness is how they stand when the enemy comes in like a flood, with the Spirit of the Lord lifting up a standard against him.