The book of Hebrews is written to the Jews, telling them that the plan of salvation has been changed. Verse 22 is the Old Covenant, the blood of the sacrificed animal was offered as atonement for their sins. Verse 28 is explaining to them that the blood of Christ has been given as atonement for all of the world's sins. He's trying to save the unbelievers among them.

This proves two separate dispensations, does it not? The blood of an animal saves no one in this age, but it did before. And it was required.

I use the Millennial to prove the point. It is more than clear that flesh survives the tribulations and passes into the Millennium. How can their salvation be based on faith in Christ alone when He is standing in front of them with His rod of iron? This would mean that all people in the Millennium are saved because they can see Him and would believe. But this isn't so, after satan is loosed from the pit, he gathers an army for the final battle.

Salvation in the Millennium is based on works alone. They are required to come to the temple and worship. They must eat from the tree of life, church age saints have the life in them.