14 Bless those who persecute you; bless and do not curse them. 15 Rejoice with those who rejoice, weep with those who weep. 16 Live in harmony with one another. Do not be haughty, but associate with the lowly.  Never be wise in your own sight. 17 Repay no one evil for evil, but give thought to do what is honorable in the sight of all. 18 If possible, so far as it depends on you, live peaceably with all. 19 Beloved, never avenge yourselves, but leave it  to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.” 20 To the contrary, “if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head.” 21 Do not be overcome by evil, but overcome evil with good. (Romans 12:14-21 (ESV)
As Bo Giertz points out in his commentary, imperatives are actually on short supply in this section that really can’t be translated correctly without use of imperatives. What we really have is a description of how love looks, and it looks like the Christian life formed by the love of Christ.
We can bless those who persecute us, because Jesus tells us we are blessed who are persecuted for his name’s sake. We can rejoice with those who rejoice because we are one with them, even as we can weep with those who weep. Notice Paul doesn’t tell us we should be happy. The Christian knows to weep with Jesus.
Live in harmony with one another. This is only possible with the forgiveness of sins. It is though something that I think needs to be emphasized. Congregations go through turmoil. Sometimes caused by pressure from outside. Sometimes from within. Congregations can become cliquish. It takes on different forms. Check it. Check it in yourself. It’s best for the congregation to be in harmony with one another. I suppose there is a time and a place for dissension. But make sure it is the gospel at stake and not your agenda. The problem I see is that most often it is a self-righteous legalism that most often causes dissension, and the people think they are helping the church. They rarely are. There is no place for power games in the church. Live in harmony with one another. We’re not here to control one another, but to be forgiven together.
Overcome evil with good. It is what Jesus did. It wasn’t pretty, but it brought about beauty.