Paul is saying they are a shadow - looking from the law towards Christ, but the substance IS Christ > and the shadows are no more. You can keep the Sabbath if you choose, but it's just a shadow. Scripture shows that rest is in Christ the Lord, not in a day.
Why are you so hung up on keeping a shadow when now we are in the Light? It is impossible to correctly observe (according to the Levitical requirements) the Sabbaths outside the ancient boundaries of Israel.
Isaiah 9:2
The people that walked in darkness have seen a great light: they that dwell in the land of the shadow of death, upon them hath the light shined.
Matthew 4:16
the people which sat in darkness saw great light; and to them which sat in the region and shadow of death light is sprung up.
Luke 1:79
to give light to them that sit in darkness and in the shadow of death, to guide our feet into the way of peace.
Hebrews 8:5
who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith he, that thou make all things according to the pattern shewed to thee in the mount.
Hebrews 10:1
For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
James 1:17
Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning.
John 3
19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil. 20 For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved. 21 But he that doeth truth cometh to the light, that his deeds may be made manifest, that they are wrought in God.
John 1:9 That was the true Light, which lighteth every man that cometh into the world.
John 8:12
Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life.
John 12:46
I am come a light into the world, that whosoever believeth on me should not abide in darkness.
2 Corinthians 4:4
in whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them.
It was prophesied that the Sabbaths would cease:
Hos 2
9 “Therefore I will return and take away My grain in its time And My new wine in its season, And will take back My wool and My linen, Given to cover her nakedness.
10 Now I will uncover her lewdness in the sight of her lovers, And no one shall deliver her from My hand.
11 I will also cause all her mirth to cease, Her feast days, Her New Moons, Her Sabbaths—All her appointed feasts
Lam 2
6 He has done violence to His tabernacle, As if it were a garden; He has destroyed His place of assembly; The Lord has caused The appointed feasts and Sabbaths to be forgotten in Zion. In His burning indignation He has spurned the king and the priest.
