New Covenant: Gotta Be
In my current look at Hebrews I see quite clearly in chapters five through ten the inadequacy of Moses' covenant. The Law established in Aaron's line a priesthood which could not approach holy ministrations with clear conscience.
There had to be blood-lettings and washings first to make the priest suitable for ministry. The animal sacrifices had to be repeated over and over because of sin and because of the deaths of the priests, all caught in "the thrall of the Fall".
But then there appeared a sinless priest, of un-designated origin after the image of Melchizedek (Genesis 14). He was able to operate under "the power of an endless life", a sinless life. He had only to offer up a sacrifice once for the sins of the people. Calvary.
Let that word ring through your heart and your consciousness - "once"!
24For Christ is not entered into the holy places made with hands, which are the figures of the true; but into heaven itself, now to appear in the presence of God for us:
25Nor yet that he should offer himself often, as the high priest entereth into the holy place every year with blood of others;
26For then must he often have suffered since the foundation of the world: but now once in the end of the world hath he appeared to put away sin by the sacrifice of himself.
(Picture depicts High Priest's breastplate with one stone in remembrance of each tribe, "carried upon the heart".)