So then, brothers, stand firm, and hold the traditions which you were taught by us, whether by word, or by letter.
Paul refers here to the teaching he did when he was with them as the church was established in Thessalonica. Now concerning this teaching, they are told to "stand fast (steko) meaning "to persevere" (Thayer 588-1-4739). He encourages the Colossians to be "Rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving" (Colossians 2:7). The necessity of standing fast or holding to the truth is often emphasized by Paul. To the Corinthians, he says, "Now I praise you, brethren, that ye remember me in all things, and keep the ordinances, as I delivered them to you" (1 Corinthians 11:2). To the church at Philippi, he says, "Only let your conversation be as it becometh the gospel of Christ:...that ye stand fast in one spirit, with one mind striving together for the faith of the gospel" (Philippians 1:27).