Matthew 5:17-18 “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. For truly I tell you, until Heaven and Earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.”
The modern church makes the mistake of going back and forth under the New and Old Covenant, often not knowing who she is or how to walk in her identity. The early church and authors of the NT understood the massive shift that had taken place.
The book of Hebrews is all about the transition from the Old Covenant to the New. (Heb. 8:13) says: "By calling this covenant ‘new’ he has made the first one obsolete”, and the new is superior to the Old and “is founded on better promises” (Heb. 8:6).
We are no longer under the Old Covenant. We're participants (by union with Christ) of a new and better Covenant (between God and Jesus). We have a perfect covenant, with a perfect lamb, a perfect high priest, established on better promises!