Jamieson, Fausset and Brown on Colossians 2:7

7. Rooted--(Ep 3:17).

built up--Greek, "being builded up." As "rooted" implies their vitality; so "builded up," massive solidity. As in the Song of Solomon, when one image is not sufficient to express the varied aspects of divine truth, another is employed to supply the idea required. Thus "walking," a third image (Col 2:6), expresses the thought which "rooted" and "built," though each suggesting a thought peculiar to itself, could not express, namely, onward motion. "Rooted" is in the past tense, implying their first conversion and vital grafting "in Him." "Built up" is present (in the Greek), implying their progressive increase in religion by union with Him. Ep 2:20 refers to the Church; but the passage here to their individual progress in edification (Ac 20:32).

stablished--confirmed.

as--"even as."

abounding therein with thanksgiving--advancing to fuller maturity (compare Col 2:2) in the faith, "with thanksgiving" to God as the gracious Author of this whole blessing.