"4 I say this in order that no one may delude you with plausible arguments. 5 For though I am absent in body, yet I am with you in spirit, rejoicing to see your good order and the firmness of your faith in Christ. 6 Therefore, as you received Christ Jesus the Lord, so walk in him, 7 rooted and built up in him and established in the faith, just as you were taught, abounding in thanksgiving. 8 See to it that no one takes you captive by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the world, and not according to Christ."
Colossians 2:4-8
Paul goes on in v 7 to explain what it means to 'continue to live in him' and he does so using a number of word pictures, metaphors of firm solidity and growth. Paul pictures the life of the believer as a tree rooted deeply and firmly in good soil, having been planted in Christ, with roots that go firm and deep to draw from Him all that is necessary for growth and development. The life of the believer is pictured as a building, built on a solid and secure foundation, built on the rock Christ Jesus, standing firm and tall when the floods come and beat against the house. These striking metaphors of a believer’s consolidation in the apostle's teaching and faith are reinforced further as Paul speaks of growth in knowledge and understanding which overflows with thanksgiving. For Paul the foundations are all important, and that at every stage of Christian experience. Indeed growth and fruitfulness only come as we are rooted and established ever more deeply in the Apostle’s teaching. At first glance it might appear strange to combine images of the Christian being established in the faith on a solid foundation, with thanksgiving. But, when you think about it, thanksgiving is the natural result of such rooting and grounding in Christ. It is as we are established more and more in the faith, as we understand more and more of what God has done for us in Christ, that our hearts overflow in thanksgiving. As we glimpse the depth of His redeeming love, so we marvel at His mercy. As we plumb the mystery of Christ, so we see our weakness and our sin over against His grace and we become ever more dependent on Him. Joyful thanksgiving and praise, then, is the language of dependence, of rootedness. It is the language of the weakest Christian in Christ, and it is only as our hearts and our minds become fixed upon Christ and upon what he has done for us, that our glad and grateful hearts will overflow in thanksgiving and praise.