The love of Christ that Christians should have is well described in Colossians 3:12-17. “Therefore, as the elect of God, holy and beloved” Therefore connects the previous verses: you have put on the new man and put off the old man, you were raised with Christ, and you are setting your mind on things above. You are the chosen of God (elect) according to your response to His calling through the word of the gospel, 2 Thessalonians 2:13-14. You are holy (sanctified) as God is holy, 1 Peter 1:15-16, and loved by the Father.
“And let the peace of God rule in your hearts, to which also you were called in one body; and be thankful.” The peace of God is to “umpire” our hearts and direct our lives. When we have peace with God, it is easier to have peace with our brethren, especially those who require more longsuffering. We are unified in one body when we all are ruled by the peace of God and seek the things which make for peace, Romans 14:19.
An example of seeking peace is in 1 Corinthians 6:1-11. I should not take my brother who has wronged me to court, but rather accept the wrong rather than disgrace the name of the Savior and the church before the world. Sometimes we have to “accept the wrong” to make for peace. It is not wrong to confront a brother for an expense resulting from his negligence, but if he will not hear you, or the church, it is better to accept the wrong and let the great Judge, our God, administer justice.