Quapropter homo, qui secundum Deum, non secundum hominem vivit, oportet ut sit amator boni; unde fit consequens ut malum oderit. Et quoniam nemo natura, sed quisquis malus est, vitio malus est: perfectum odium debet malis, qui secundum Deum vivit, ut nec propter vitium oderit hominem nec amet vitium propter hominem, sed oderit vitium, amet hominem. Sanato enim vitio totum quod amare, nihil autem quod debeat odisse remanebit.
“For this reason, the man who lives by God’s standards and not by man’s, must be a lover of the good, and it follows that he must hate what is evil. Further, since no one is evil by nature, but anyone who is evil is evil because of a perversion of nature, the man who lives by God’s standards has a duty of “perfect hatred” (Psalms 139:22) towards those who are evil; that is to say, he should not hate the person because of the sin, nor should he love the sin because of the person. He should hate the sin, but love the man. And when the sin ceases to exist there will remain only that which he ought to love, nothing that he should hate.”
–St. Augustine of Hippo (d. 430), City of God, 14.6