And this I say, lest any man should beguile you with enticing words.
Note 20 at Col 2:4: Here, Paul was at the heart of the reason he wrote this epistle. He wanted the Colossians to be so grounded in the truth that no one could move them from their faith in Christ. He did this not so much by attacking all the potential errors but by expounding on the truth--specifically the truth of "Christ in you, the hope of glory" (Col 1:27).
Once we get the revelation that Christ is in us in His fullness and that we are complete in Him, how can we ever move away from this truth? To what can it compare? Those who have left their faith in Christ for something else never fully appreciated what they had. As David said, "O taste and see that the Lord is good" (Ps 34:8). Once people have truly "tasted" the goodness of the Lord, nothing else will satisfy.
Note 21 at Col 2:4: The word "beguile" means "to deceive...cheat...divert" (American Heritage Dictionary). Satan's strongest attack is not a frontal assault against the truths of the Gospel; rather, he uses subtle deception. Perversion of the truth has captured more people than an outright denial of truth (see note 8 at Ga 1:7).
Note 22 at Col 2:4: Notice that Paul was warning against the enticing words that the Enemy was using to turn their hearts away from the Truth. Satan didn't use the biggest, most powerful animal to approach Eve and tempt her; he used the most cunning (Ge 3:1). That's because he had no power or authority to force Adam and Eve to do anything. He had to deceive them and get them to destroy themselves. That's the way it is with us.
Satan can't force any one of us away from the Truth. He has to deceive us, and he uses words to accomplish that. We need to be aware of this and protect ourselves by diligently guarding our hearts against any words that oppose the truth of God's Word. We can't do that if we are not thoroughly acquainted with God's Truth. Therefore, as Paul was arguing here, we need to be grounded in the foundational principles of the Gospel (see note 20 at this verse).