6-7 So then, just as you received Christ Jesus as Lord, continue to live your lives in him, rooted and built up in him, strengthened in the faith as you were taught, and overflowing with thankfulness. 8-10 See to it that no one takes you captive through hollow and deceptive philosophy, which depends on human tradition and the elemental spiritual forces of this world rather than on Christ. For in Christ all the fullness of the Deity lives in bodily form, and in Christ you have been brought to fullness. He is the head over every power and authority. 

11-12 In him you were also circumcised with a circumcision not performed by human hands. Your whole self ruled by the flesh was put off when you were circumcised by Christ, having been buried with him in baptism, in which you were also raised with him through your faith in the working of God, who raised him from the dead. 13-14 When you were dead in your sins and in the uncircumcision of your flesh, God made you alive with Christ. He forgave us all our sins, having cancelled the charge of our legal indebtedness, which stood against us and condemned us; he has taken it away, nailing it to the cross.  15 And, having disarmed the powers and authorities, he made a public spectacle of them, triumphing over them by the cross.

16 Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. 17 These are a shadow of the things that were to come; the reality, however, is found in Christ.  18 Do not let anyone who delights in false humility and the worship of angels disqualify you. Such a person also goes into great detail about what they have seen; they are puffed up with idle notions by their unspiritual mind. Colossians 2:6-18 New International Version

There are religious groups today who teach that, while you need to BEGIN with Jesus, you can only be saved if you join their group and follow the rules they dish out. Some even require that their followers must put in a number of hours of service to their cause. So their message is believe in Jesus - PLUS whatever else they command you to do. The Christians at Colossae were facing a similar problem. Some people among them were teaching that believing on Jesus Christ and what He accomplished on the cross was not enough to make them righteous in God's sight. They said men needed to be circumcised and all Christians must not eat certain foods. They also insisted on keeping special festivals and ‘holy’ days. What was the apostle Paul's main argument against all such teaching? (vs 8-10)

Because God was fully in Christ, those who have put their faith in Jesus have everything they need to be saved already given to them in Him. Both Jesus, and the sacrifice He made on the cross, are perfect. Look how clearly Paul states that in vs 13-14. No wonder that just before Jesus expired He cried out “It is finished!” The work of salvation was complete.

But some of the false teachers objected that things like circumcision and keeping the Sabbath, and many other rules, were actually in the Bible, so they must be necessary. But what does Paul point out in vs 17.

Those things were just shadows cast by the shining reality of what was to come. They were preparations for Messiah's coming, but no longer needed now that He had fulfilled them all. What is a common danger of those who insist on keeping their strict rules? (vs 18)

They often base their claims on angels and visions and are puffed up with their own self importance. Instead of pointing others to Jesus Christ they magnify themselves and their so called revelations. In vs 8-10 Paul says their teachings are hollow and deceptive products of man made “wisdom”. What does Paul say Christians should do after they have believed on Christ for salvation? (vs 6-7)

They must stay rooted in Christ and hold on to the apostolic truth they had received. This message is as important today as it was then. We don't need Jesus PLUS whatever the sects or TV evangelists add to the gospel. We are complete in Christ. Hallelujah!