In verse 8, the word translated as "basic principles of the world" refers to elementary things. Compared to Christ, in terms of being, every other being is lesser because he or she is created. In terms of teaching, every other instruction is elementary, basic, even demonic. In terms of salvation, no other is able to save human beings.
In verses 9-10, Paul again emphasizes Christ's primacy and superiority, including the facts that He is divine and over demons in authority. He adds in verses 11-15 that, for Christians, Jesus has already defeated the principalities and powers, along with their purposes, through their conversion.
As Colossians 1:16 states, Christ's rank extends back to the very beginning, as the One used to create all things. Thus, He is the God (John 1:1) referred to in nearly every place in the Old Testament where God is mentioned. This is especially important to grasp.
John 14:10 aids us in understanding His operations as a man: "Do you not believe that I am in the Father, and the Father in Me? The words that I speak to you I do not speak on My own authority; but the Father who dwells in Me does the works." Matthew 26:52-53 clarifies this through an example: "But Jesus said to him, 'Put your sword in its place, for all who take the sword will perish by the sword. Or do you think that I cannot now pray to My Father, and He will provide Me with more than twelve legions of angels?'"
While He was human, His power as a God-Being was suspended as part of His emptying Himself to become a man (Philippians 2:5-8). He thus operated on the same level as all other men, except for the innate power He possessed due to His divine nature, enabling Him to live by faith sinlessly. Better than all other men, He understood the purpose God is working out, and He believed it. Notice to whom He said He could turn in time of need.
John W. Ritenbaugh
Power Belongs to God (Part Two)
"As you have been taught" refers to what Epaphras and Tychicus had taught the Colossians. Paul wanted them "abounding in it"—growing, producing fruit, and not deviating from it.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part Twenty)