Are you suggesting Hebrews is not applicable to Christians??
2Ti 3:16 All scripture is inspired by God, and is beneficial for teaching, for exposure, for correction, for discipline in righteousness.
Not all was written TO us. The Scrolls of the various New Testament writers were sent to particular people. It is imperative to know and understand this truth or confusion and error will persist in one’s beliefs.
Only Paul was commissioned for the Gentiles, not the other apostles. They failed and God locked them all up in stubbornness til the era of the Gentiles is filled up.
2Ti 2:15 Endeavor to present yourself to God qualified, an unashamed worker, correctly cutting the word of truth.
2Ti 2:16 Yet from profane prattlings stand aloof, for they will be progressing onto more irreverence.
It is unfortunate that prattling is all that some who frequent here can muster. Honesty and sincerity are at a discount. We all get what we deserve according to our faithfulness. It is in service to God that worth is determined, ego plays no role whatsoever.