William Burkitt on Romans 12:17

By evil here, we are to understand wrongs and private injuries; by not recompensing them, is meant not revenging them. Corrupt nature is very prone to return wrong for wrong, one ill turn for another, but Christianity sets a nobler pattern before us, even the example of him, "who when he was reviled, reviled not again, when he suffered, he threatened not," Provide things honest in the sight of all men. 1Pe 2:23.

Having exhorted them before to be careful of their conversations towards God, he now presses them to be watchful over their conversations before the world, that by honesty and innocency of life they may cut off all occasion from the enemies fo religion to speak evil of them, and their holy profession; that all their words and actions be justifiable and unexceptionable, to that degree that the heathens may be in love with Christianity, by observing their lives and actions to be holy and honest.

Learn hence, That a Christian must carefully look, not only to his conscience, but to his conversation; that his conscience be holy and upright in the sight of God, and his conversation honest and unblameable before men. The world cannot discern our hearts, but they can soon discover the errors of our lives, and will throw the dirt of our sins upon religion's face; therefore we had need provide things honest in the sight of all men.