Colossians 2:8-10 gives another general definition of Gnosticism, as well as how to combat it. Paul is writing about a philosophy like Stoicism, not a specific religion, such as Judaism. This is important to recognize, since in verse 16, Paul mentions the Sabbath and holy days, and it is commonly assumed that Paul condemns their observance. Yet, he does not - he warns against a philosophy that disparaged the feasting and joyous observance of the Sabbath and holy days. This is why Paul tells the Colossians to "let no one judge you" with regard to eating, drinking, or observing the weekly and annual Sabbaths - rather than what is commonly read into Colossians 2:16: "There is no reason to keep the Sabbath or holy days." Christians in Colossae were being pressured by the ascetic society around them, which would have looked down on their feasting.
This is confirmed in the rest of Colossians 2, which deals primarily with asceticism (see especially Colossians 2:21-23). Some branches of Gnosticism adhered to asceticism as a way to free the eternal spirit by living regimented, plain, and insular lives. (Conversely, some Gnostics went to the other extreme - practicing hedonism - believing that what they did with their bodies did not make any difference since only spirit mattered.)
Paul says that this philosophy and its associated doctrines were plausible, but they were not based on solid arguments. He calls them "vain deceit" (KJV) or "empty deceit" (NKJV). They may sound good, depending upon one's inclination, but they endanger church members. The apostle writes that they would be "spoiled" (KJV), which does not necessarily mean being "corrupted," but rather of being "plundered," hence the NKJV's use of "cheated." This empty philosophy would rob or cheat them of their faith, their hope, their understanding of God, their relationship with God, their vision, and the purpose that God is working out. Once introduced, it would begin to steal away all of their true, spiritual riches.
Paul also provides two possible sources of this unsteady philosophy: "the traditions of men" and the "rudiments of the world." Examining the "rudiments of the world" first will help to explain the traditions of men. Other translations call them the "elements of the world," the "basic principles of the world," or "the powers of the world." In using this term, Paul is referring to the demonic powers that make this world, this cosmos, what it is. The source of this philosophy of salvation through special knowledge is Satan and the demons.
This explains why, when we read the histories of various religions and their branches, the same patterns arise time and again. Man does not have it within himself to pass along accurately and dependably ideas that go back to the very beginning. With an incessant drumming, the powers of the world keep prompting men and women in the same vain deceits that directly contradict the truth about God and His purpose for mankind.
Humans certainly play a role in handing down these traditions. Sunday school teachers and theologians perpetuate the Gnostic myths of the immortality of the soul, of eternal consciousness, of progressive revelation, of each person having a spark of goodness within that just needs to be fanned into a flame, and of each soul or spirit existing before in heaven and returning there upon death. Men pass these traditions on to other men, but the powers of the spirit world keep these messengers on their track and blinded to the truth.
The last phrase in Colossians 2:8 - "not according to Christ" - is a simple one, but it encapsulates what this is all about. Not a single branch of Gnosticism had the truth about Jesus Christ. That knowledge can be found only in God's Word.