In having put off our old selves (3:5-11), Paul points us to the new nature to clothe ourselves in daily: Christ’s. If we live in our identity as chosen, holy, and beloved because of Him (and not our own striving), we are moved to behave in a strange new way, full of compassion, kindness, humility, meekness, and patience; overcome by peace and filled with gratitude.
Put on then, as God’s chosen ones, holy and beloved, compassionate hearts, kindness, humility, meekness, and patience, bearing with one another and, if one has a complaint against another, forgiving each other; as the Lord has forgiven you, so you also must forgive. And above all these put on love, which binds everything together in perfect harmony. And let the peace of Christ rule in your hearts, to which indeed you were called in one body. And be thankful.