D. A. Carson, Love in Hard Places (Wheaton: Crossway, 2002), pp. 52–57 (numbering added):

Not all Christians face persecuting enemies, but all Christians face little enemies. We encounter people whose personality we intensely dislike—

1. an obstreperous deacon or warden or bishop;
2. a truly revolting relative;
3. an employee or employer who specializes in insensitivity, rudeness, and general arrogance;
4. a business competitor more unscrupulous, not to say more profitable, than you are;
5. the teenager whose boorishness is exceeded only by his or her unkemptness;
6. the elderly duffers who persist in making the same querulous demands whenever you are in a hurry;
7. the teachers who are so intoxicated by their own learning that they forget they are first of all called to teach students, not a subject;
8. the students so impressed by their own ability or (if they come from certain cultures) so terrified by the shame of a low grade that they whine and wheedle for an “A” they have not earned;
9. people with whom you have differed on some point of principle who take all differences in a deeply personal way and who nurture bitterness for decades, stroking their own self-righteousness and offended egos as they go;
10. insecure little people who resent and try to tear down those who are even marginally more competent than they;
11. the many who lust for power and call it principle;
12. the arrogant who are convinced of their own brilliance and of the stupidity of everyone else.

The list is easily enlarged. They are offensive, sometimes repulsive, especially when they belong to the same church. It often seems safest to leave by different doors, to cross the street when you see them approaching, or to find eminently sound reasons not to invite them to any of your social gatherings. And if, heaven forbid, you accidentally bump into such an enemy, the best defense is a spectacularly English civility, coupled with a retreat as hasty as elementary decency permits. After all, isn’t “niceness” what is demanded? . . .

In many instances, what is required is simply forbearance driven by love. No one puts it more forcefully than Paul: “Therefore, as God’s chosen people, holy and dearly loved, clothe yourselves with compassion, kindness, humility, gentleness and patience. Bear with each other and forgive whatever grievances you may have against one another. Forgive as the Lord forgave you. And over all these virtues put on love, which binds them all together in perfect unity” (Col. 3:12–14). To bear with one another and to forgive grievances presupposes that relationships will not always be smooth. Most of the time, what is required is not the confrontation of Matthew 18, but forbearance, forgiveness, compassion, kindness, humility, gentleness, or patience. Christians are to mourn with those who mourn and rejoice with those who rejoice (Rom. 12:15). . . .

That brings us to three reflections.

First, this loving of awkward people, first of all those within the household of faith but then also outsiders, is sometimes grounded not on God’s providential love (as in Matt. 5:43–47), but on a distinctively Christian appeal. . . . “Forgive as the Lord forgave you”—a frank appeal to the Christian’s experience of grace.

Second, in practical terms this love for “little enemies” is sometimes (though certainly not always) more difficult than love for big enemies, for persecuting enemies. . . .

Third . . . there is a frankly evangelistic function to Christian love.