"Love must be sincere. Hate what is evil; cling to what is good. Be devoted to one another in brotherly love. Honor one another above yourselves. Never be lacking in zeal, but keep your spiritual fervor, serving the Lord. Be joyful in hope, patient in affliction faithful in prayer. Share with God's people who are in need. Practice hospitality. Bless those who persecute you; bless and do not curse. Rejoice with those who rejoice, mourn with those who mourn. Live in harmony with one another. Do not be proud, but be willing to associate with those of low position. Do not be conceited. Do not repay anyone evil for evil. Be careful to do what is right in the eyes of everybody. If it is possible, as far as it depends on you live at peace with everyone. Do not take revenge, my friends, but leave room for God's wrath, for it is written:'It is mine to avenge; I will repay,' says the Lord." Romans 12:9-19
The chapter goes on to say that not only do we not take revenge, we feed those who are our enemies and give them something to drink. Rather than being overcome by evil, we are to overcome evil with good. I think these verses are an example of God's thoughts being higher than ours, as stated in Isaiah 55. These things do not come naturally to us in our flesh. They take prayer, faith, and God working in us.
My prayer for people at my church, and for any of you holding a grudge, is that God will heal you of that and forgive you so you can fully experience his peace that is beyond our understanding.