Colossians: Complete in Christ
Christ is sufficient. Christ is preeminent (surpassing all others). Christ is the firstborn of every creature. All things were created by him and for him. He is before all things; in him all things consist. All the fullness of Godhead dwelled in him bodily. All treasures of wisdom and knowledge are hidden in him. He is the head of all principalities and power. Christ is sufficient.
We are in Christ, meaning we are in the one who is preeminent, in the one who was before all things, in the one who has all the treasures of wisdom and knowledge, etc. We then are complete in Christ and complete only in Christ.
Through Christ Jesus we will be presented perfect before God.
This is why we must abide (remain) in Christ. Yes, our natural man moves around, travels, and works, but our spiritual man should never cease to abide in Christ alone. The danger facing the Colosse church was that false teachers, popular philosophy, and self-made religion were threatening to remove them from finding sufficiency and completion in Christ alone.