In that he says, A new covenant, he has made the first old.     Now that which decays and waxes old is ready to vanish away. Heb 8:13 Paul preached the Gospel of Grace Through Faith which stands completely on its own with no dependence on prior covenants or standards for righteousness.      However, some believers then and now still hang on to performance aspects of the law as requirements for Spirit Salvation.     This is error.      Forgiveness of sins is a done deal Heb 8:12.      Eternal Life in the New Birth comes by faith in Christ Jesus Rom 6:23.      We then walk by faith in the Word so that we experience Abundant Life Joh 7:38.      Salvation is two-part: Spirit Salvation and Soul Salvation.

The Old Covenant is constantly being resurrected by those who doubt the Grace of our Lord.   

Such that believe that we have a part in our salvation go back to the old ways and old understanding.   

The old cloth is unfit for use in the New Covenant.   
The old wineskin is unfit for use in the New Covenant.   

That being said, for those who doubt the Grace of our Lord, the Old Covenant provides a fall-back.   

For whoever shall keep the whole law, and yet offend in one point, he is guilty of all. Jam 2:10 walking by sight puts you back into the Physical Realm of the law.

This is the sad truth for those who doubt the Grace of the Lord: They must keep the whole law perfectly in order to be accepted.   

So, despite the fact the Old Covenant has been superceded by the New Covenant, those who drag it back up keep it alive in their minds.