Rooted ...in him - As a tree strikes its roots deep in the earth, so our faith should strike deep into the doctrine respecting the Saviour. See the phrase used here explained in the parallel place in Ephesians 3:17.
And established in the faith, as ye have been taught - To wit, by the founders of the church, and by those faithful ministers who had succeeded them; Notes, Colossians 1:7.
Abounding therein with thanksgiving - Expressing overflowing thanks to God that you have been made acquainted with truths so precious and glorious. If there is any thing for which we ought to be thankful, it is for the knowledge of the great truths respecting our Lord and Saviour.