20 You have died with Christ, and he has set you free from the spiritual powers of this world. So why do you keep on following the rules of the world, such as, 21“Don’t handle! Don’t taste! Don’t touch!”? 22Such rules are mere human teachings about things that deteriorate as we use them. 23These rules may seem wise because they require strong devotion, pious self-denial, and severe bodily discipline. But they provide no help in conquering a person’s evil desires
In verse 20, we see a one part summary of the work that happens to us at salvation. A full explanation is presented in Romans 6: 3-12
have you forgotten that when we were joined with Christ Jesus in baptism, we joined him in his death? 4For we died and were buried with Christ by baptism. And just as Christ was raised from the dead by the glorious power of the Father, now we also may live new lives.
5Since we have been united with him in his death, we will also be raised to life as he was. 6We know that our old sinful selves were crucified with Christ so that sin might lose its power in our lives. We are no longer slaves to sin. 7For when we died with Christ we were set free from the power of sin. 8And since we died with Christ, we know we will also live with him. 9We are sure of this because Christ was raised from the dead, and he will never die again. Death no longer has any power over him. 10When he died, he died once to break the power of sin. But now that he lives, he lives for the glory of God. 11So you also should consider yourselves to be dead to the power of sin and alive to God through Christ Jesus.
The work at salvation can be likened to marriage. When a man and a woman are joined together in marriage, they are one and if she goes to be someone even after divorce, it is adultery. Thus for her to truly and rightly join with someone else one of them have to die to come out of the covenant. This applies to our relationship with the life of sin into which we were born and thus sinners by nature; to leave this life, it is not enough to just renounce sin i.e. divorce it but we need to die to be completely separated from that covenant. This is why Christ died, he took our place on the cross and because we are in him we died along with him and when he resurrected, we resurrected with him free of our former commitment to the life of sin and now in a loving, covenant relationship with God.
Now having been separated from our old husband or master through death and now married with Jesus, doesn’t it seem wrong to still be moved with rules from our old husband? Its like breaking up with an ex, dating someone new and still going to wash plate for the ex, weird right? That's what it feels like when we who have been separated from the world try to go back to it by following traditions of men.
In 23 Paul presents to us why it is so easy to fall prey of these instructions - it is because they seem difficult and pious and we thus equate it to be holy because we expect holy things to be difficult.
“WHAT is here termed will-worship, eyeloyrhskeia, signifies simply a mode of worship which a man chooses for himself, independently of the revelation which God has given...God will be served in his own way; it is right that he should prescribe to man the truths which he is to believe, and the ordinances which he is to use. To refuse to receive his teaching in order to prefer our own fancies, is to light a farthing candle as a substitute for the noonday sun. From the beginning of the world God has prescribed the worship which was best pleasing to himself, and never left a matter of such moment to man.” - Adam Clarke’s Commentary
God has prescribed how we would worship him in John 4:24 (For God is Spirit, so those who worship him must worship in spirit and in truth.) and thus trying to add our own is a form of pride like we know what the most high would want.
“Much affected sanctity may exist where there is a most proud and corrupt heart. A long face, a demure countenance, a studied disregard of the decencies of dress and the courtesies of life, as if they were unworthy of notice, may be the exponent of the most hateful pride, and of the basest purposes of the soul.” - Albert Barnes NT Commentary
No individual has a right to appoint ceremonies and ordinances in the church to be binding on the consciences of others; nor is this authority entrusted to any body of men, Col 2:16. What God has enjoined is to be obeyed. What man enjoins beyond that, is of no binding force on the conscience; and it is the solemn and sacred duty of all Christians to resist all such attempts to make ceremonial observances binding on the conscience. Christ has appointed a few ordinances of religion, and they are enough. They are simple, easily observed, and all adapted to promote piety. He appointed baptism and the Lord's Supper; but he appointed no stated festivals or fasts; no days in commemoration of the saints, or of his own birth or death; he enjoined no rites of religion but those which are most simple, and which are easily observed...We should not attempt to penetrate into those things which lie beyond the grasp of the human mind, Col 2:18. We should not "intrude into those things which are unseen." There is an outer limit to our investigations on all subjects, and we soon reach it. In life we are to act chiefly on facts; not on the reason why those facts exist. When we have ascertained or established a fact, our feet stand on a solid rock; and there we shall stand securely. We act safely and wisely if we act in view of that fact; we do not act safely or wisely if we disregard that, and act on theory or imagination. - Albert Barnes NT Commentary