This theme incorporates much of what we have learned in Colossians 2: the defrauders were trying to persuade the Colossians to their way instead of God's way. Paul's mission in this chapter was to warn the Colossians against this and remind them of what salvation truly is.
Here are a few other themes I considered:
Stability of Faith (2:4-5)
Nailed to the Cross (2:13-14)
The Appearance of Wisdom (2:23)
What theme did you pick for Colossians 2?
Monday we will begin Colossians 3, a powerful chapter that discusses how the Colossians should live since they have died and been raised to a new life (2:20-23).