What does Colossians 2:19 mean?
Here Paul transitions to a word picture of the human body. The collection of all Christian believers is what the Bible refers to as the church. If that church is imagined as a physical body, then Christ is the Head. Those who Paul refers to as "puffed up" (Colossians 2:18) are not connected to the Head—they are not part of the actual body with Christ. These false teachers think they can grow spiritually when they are separated from Jesus. This is as impossible as a part of the body growing or developing when totally severed from the head!Paul also reminds the Colossian believers that God provides two important elements to our Christian life. First, God is the one who causes growth. True spiritual progress does not occur through requiring ascetic practices (Colossians 2:18), or rituals (Colossians 2:16), but in following Christ. The more we rely on our own power and ability, the less we allow Christ to use His power in us. This is the problem with mysticism and self-denial: they rely on our own strength, instead of the power of Christ.
Second, Paul explains that our common dependence on Christ produces both growth and unity. Unity must be built upon God and His teachings in order to be genuine. The idea of "knitting together" was also mentioned in Colossians 2:2 in relation to God providing unity in love.
Colossians 2:16–23 is an application of the ideas Paul mentions in the previous verses. Verses 6 through 15 explained the supremacy of Christ over deceptive, human-based thinking. In this passage, Paul explicitly states that rules, rituals, and self-denial are not the path of spiritual growth. Trying to grow, spiritually, through these efforts is as impossible as a body part developing naturally while severed from the head! Living under severe rules might look good to others, but it's not how God has called us to relate to Him as Christian believers.
In this passage, Paul warns Christians not to be taken in by deceptive arguments. These claims are attractive, but are merely tricks: they sound true, but they are not. Arguing for self-denial, legalism, visions, and other practices only looks good to observers. None of these are the real source of spiritual growth. Paul emphasizes the way Christ accomplished everything we need to be justified before God. As a result, there is no reason for believers to pursue these false, shallow ''shadows.'' We have the real substance: Jesus, so we should follow Him.