"16 Therefore let no one pass judgment on you in questions of food and drink, or with regard to a festival or a new moon or a Sabbath. 17 These are a shadow of the things to come, but the substance belongs to Christ. 18 Let no one disqualify you, insisting on asceticism and worship of angels, going on in detail about visions, puffed up without reason by his sensuous mind, 19 and not holding fast to the Head, from whom the whole body, nourished and knit together through its joints and ligaments, grows with a growth that is from God.
20 If with Christ you died to the elemental spirits of the world, why, as if you were still alive in the world, do you submit to regulations— 21 “Do not handle, Do not taste, Do not touch” 22 (referring to things that all perish as they are used)—according to human precepts and teachings? 23 These have indeed an appearance of wisdom in promoting self-made religion and asceticism and severity to the body, but they are of no value in stopping the indulgence of the flesh."
Colossians 2:16-23
In these verses Paul exposes and refutes a wrong way of living which purports to be authentic Christian living. He exposes and refutes the false piety, which is the outworking of the empty and deceitful philosophy of the 'heretics'. By so doing, Paul is specifically applying the implications of this objective redemption 'in Christ' to the particular matters of concern which arise from the false philosophy and false practices advocated by the heretics. You will notice that these are negative injunctions, they are exhortations 'not to' (it is not until ch. 3 that Paul comes to the positive exhortations). Salvation says 'no' to certain ways of living and thinking before it ever says 'yes' and in the particular situation of Colossae, Paul targets his guns on the false teachers, on the practices they advocate and on the false notions of piety which underlie these practices.