As we read Colossians 2:16-17, we see Old Testament practices pointed people to Jesus. Jesus is the ultimate characterization of them, hence the term fullness. One of these practices is the sabbath, an eternal sign of God's covenant with Israel. It was the sabbath concept being dropped for 490 years that lead to Israel being exiled from the land, so it may receive its 70 year rest. It is not a far stretch to say sabbath is a serious concept. But in this verse we see we are not to be judged on it, and that Christ is the fullness of it.
Paul is teaching us that Jesus is the Christian sabbath. As God completed his work and rested on the seventh day, on the cross Jesus completed the work of salvation by dying once for all sin. It is finished, he stated. The mark of the new covenant isn't sabbath keeping or circumcision, but the indwelling of the Holy Spirit who keeps, enlightens, and seals the believer until ultimate salvation when Jesus returns. Many people are anxious in their spiritual lives because they're not resting in Christ. When that happens they will fall into a false religion or a false gospel. Rather than, in Christ, cease their work towards heaven, they strive for an objective already completed on the cross.
This week we will continue to look at our need to trust and rest in God.