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.