Charles H. Spurgeon on Psalms 139:21

Do not I hate them, O LORD, that hate thee? He was a good hater, for he hated only those who hated good. Of this hatred he is not ashamed, but he sets it forth as a virtue to which he would have the Lord bear testimony. To love all men with benevolence is our duty; but to love any wicked man with complacency would be a crime. To hate a man for his own sake, or for any evil done to us, would be wrong; but to hate a man because he is the foe of all goodness and the enemy of all righteousness, is nothing more nor less than an obligation. The more we love God the more indignant shall we grow with those who refuse him their affection. "If any man love not the Lord Jesus Christ let him be Anathema Maranatha." Truly, "jealousy is cruel as the grave." The loyal subject must not be friendly to the traitor. And am not I grieved with those that rise up against thee? He appeals to heaven that he took no pleasure in those who rebelled against the Lord; but, on the contrary, he was made to mourn by a sight of their ill behaviour. Since God is everywhere, he knows our feelings towards the profane and ungodly, and he knows that so far from approving such characters the very sight of them is grievous to our eyes.