The Colossian believers were being threatened with a false and deceptive philosophy (2:4, 8). This deviant religious teaching was not according to Christ and His teaching. It did not recognize Him as all one needs to be saved and grow spiritually (1:19-22; 2:9-10, 19). The false and deceptive teachers peddled legalism (2:16-17), mysticism (2:18-19), and asceticism (2:20-23) as other components necessary to please God.
Asceticism is the practice of denying oneself the pleasures of the world for religious purposes. An ascetic might not only abstain from certain foods and drinks, but even neglect or severely treat his body in order to restrain the sinful impulses of the body and attain a high form of spirituality. But Paul said that these kinds of pursuits are of no value against the indulgences of the flesh (2:23). What does enable us to be victorious over sin is union with Jesus Christ! Since we died with Christ (2:20), and were raised to new life with Him (2:12, 3:1), we can put off the old man with his sinful deeds and put on the new man with his righteous deeds. It is only in Christ that we have life, and have it abundantly!