Well, here’s my attempt to summarize the letter:
Short summary: Paul’s intent is to encourage his readers to grow in their faith and to warn them against falling captive to hollow philosophies or attitudes that might lead them astray. They must instead hold onto the message they received about their Lord Jesus Christ, continuing to grow into him, embracing his qualities, and overflowing with thankfulness (some key verses being 1.9-12; 1.15-20; 2.2, 4; 2.6-8; 3.10, 12-14).
Longer version: Paul wants his readers to continue to mature in their faith, growing in knowledge of God’s will, which primarily entails understanding of the person and work of Jesus Christ. Knowing Christ in this way puts one in a proper position to live a life that is pleasing to the Lord (1.9-12; 1.15-20; 2.2; 2.6-8).
Nothing and no one compares to the Lord Jesus Christ—He is God made known to mankind. It is through him that we experience reconciliation to God and the forgiveness of sins. He has reconciled us to himself and is in the process of redeeming all of humanity and all of creation, bringing the whole world together in unity. All things fall under the scope of his Lordship. Praise him (1.13-20).
Jesus alone brings true spiritual fulfillment; therefore, we must remain connected to him and continue to grow into him. We must not allow ourselves to be duped by hollow ideas or new fads that diminish the importance of Jesus Christ. Nor must we allow ourselves to get hung up on the observance of religious practices; such things don’t bring about righteousness, which comes only through Christ (2.2-3; 6-8; 9-23).
We must rid ourselves of everything that is inconsistent with his character and embrace all that he embodies: compassion, kindness, humility, gentleness, patience, peace, and self-sacrificing love. Putting on Christ—“the new self”—starts in the home and in our everyday relationships. Remember to always place others’ needs ahead of your own, and lay down your lives for one another in reverence to your Lord Jesus Christ (3.1-25; 4.1).
We participate in Christ’s ministry of reconciliation when we put such virtues into practice. In fact, our speech and actions serve as a testimony and as an expression of Christ’s grace. Our faith should be compelling and attractive to those outside the faith community (4.5-6).
And let us not forget, as the letter attests again and again, that we ought to be thankful for all Christ has done for us and is doing in our midst. Pray that the message of Christ continues to be revealed so that the entire world may be impacted by his mercy and grace, and thereby experience the redemption and new life that can be had in him (4.2-4; 1.12-14; 1.20-22).
Grace be with you