What does genuine love look like? Paul first says that it is discerning, able to tell the difference between what is evil and what is good. Moreover, it feels strongly about both areas and is not indifferent about them.
Paul expects the Roman Christians to have a very strong attitude towards what is evil – such things are to be loathed. We cannot be indifferent about or only have a slight dislike for such things. Instead a person with genuine love will detest things that are evil, whatever they are.
This strength of feeling against evil indicates that a Christian has discovered that evil is the opposite of the character and beauty of God as well as being a constant danger to a Christian’s progress in holiness.
In the context Paul is telling his readers that evil of any kind will prevent genuine love if it is not treated with the correct attitude. So how do we know what to abhor? I would suggest that the answer to that question is not difficult. We should abhor all ways by which the Ten Commandments, or God’s law, are broken. Virtually everything in life can be assessed by the Ten Commandments and we should have no difficulty in identifying things that are wrong and which we should detest.
In contrast, Christians are to cling to what is good. Good here is the practice of godly principles. In everyday life we hold on to what is valuable because someone is trying to steal it; or we hold on to something important because the wind is liable to blow it away. Today we are under pressure to call evil good and to let go of what is truly good. If we give it away easily, it means that we do not value them and are willing to let God's standards go. And it would mean that we do not possess genuine love.