False teachers in Colossae were teaching philosophies and empty deceit that are based on human traditions. They seek to "kidnap" Christians from Christ by their false teachings that are not according to Christ.
They teach the elemental principles of works-based religion- consisting of food and drinks regulations; observances of festivals, sabbaths and new moons; and severity to the body and asceticism, amongst other things. These beliefs and practices are not in accordance to the gospel of grace, but are legalistic and self-righteous. These things do not save. They also do not confer "extra spirituality."
Paul therefore warns them to watch out for these false teachings. In essence, he reminds them that in Christ, they have everything. But apart from Christ, they have nothing. Jesus is the source of all wisdom and knowledge. He is the reason why we can have power over sin, and how we are delivered from the penalty of sin.
