Paul tells them the key to remain unified is to show compassion and forgiveness toward one another.
12 Since you are all set apart by God, made holy and dearly loved, clothe yourselves with a holy way of life: compassion, kindness, humility, gentleness, and patience. 13 Put up with one another. Forgive. Pardon any offenses against one another, as the Lord has pardoned you, because you should act in kind. 14 But above all these, put on love! Love is the perfect tie to bind these together. 15 Let your hearts fall under the rule of the Anointed’s peace (the peace you were called to as one body), and be thankful.
16 Let the word of the Anointed One richly inhabit your lives. With all wisdom teach, counsel, and instruct one another. Sing the psalms, compose hymns and songs inspired by the Spirit, and keep on singing—sing to God from hearts full and spilling over with thankfulness. 17 Surely, no matter what you are doing (speaking, writing, or working), do it all in the name of Jesus our Master, sending thanks through Him to God our Father.