9 Let love be genuine. Abhor what is evil; hold fast to what is good.
Abhor [hating] what is evil;
It may be that “abhor what is evil” and “hold fast to what is good” may further explain “let love be genuine.” “Abhor” is a strong Greek term—hate fiercely. It is not adequate to tolerate evil; we must take the further step to hate it. Covering up evil is not a proper Christian value. Treating evil civilly is not a good idea. A lukewarm approach to evil will ultimately destroy the believer. Most Christians today will acknowledge that sin is evil but they do not hate it. This phrase is a call to hold a revulsion attitude toward evil.
Ps 97: 10 You who love the Lord, hate evil! He preserves the souls of His saints; He delivers them out of the hand of the wicked.
It is important to hate some things.
Some things the believer should shrink back from. Is anything abhorrent to Christians anymore? Some things should be repulsive to us and we should hate them. There are things we need to thoroughly hate. Before we became Christians we loved sin and its entire culture. Now we hate the things we loved. The more we grow in grace the more we will hate sin.