When I see the blood, I will pass over you (Exodus 12:13. New King James Version). This was the promise of God to His people when the angel of death was sent to kill the first born children in Egypt
Why blood? Why not tears or an oath? What is so special about blood? Because everything on the outside can be faked, as any trial judge would tell you, which is why they love DNA evidence and which is why God looks on the inside rather than on the outside, But the Lord said to Samuel, “Do not look at his appearance or at his physical stature, because I have refused him. For the Lord does not see as man sees; for man looks at the outward appearance, but the Lord looks at the heart.” (1 Sam 16:7).
Blood is very much the 'heart’ of the matter; not tears or testimony or anything external can save us, which means that we have to give our hearts (inside), not only our bodies (outside). There is no room for hypocrisy. Real relationship is what God is looking for, not religious rituals. The need for blood equals the difference between the fig leaves (man’s effort) in Gen 3:7, Then the eyes of both of them were opened, and they knew that they were naked; and they sewed fig leaves together and made themselves coverings and God’s solution (tunics of skin) Gen 3:21, Also for Adam and his wife the Lord God made tunics of skin, and clothed them.
From the very beginning, real atonement involved death. Even so, at the present, atonement involves death and the shedding of blood, For where there is a testament, there must also of necessity be the death of the testator (Heb 9:16).The only difference is that now, it is not the death of goats and bulls but the death of Jesus that is required.
Why Jesus? The tunics of skin that God used as atonement, as cover for sin in Genesis 3:21 were temporary as is the blood of bulls and goats. It is impossible for the blood of animals to take away our sin (Heb 10:4). And the reason is not far to seek; they are not permanent, reminding us each time,of sin But in those sacrifices there is a reminder of sins every year (Heb 10:3).
What will suffice? Only the blood of Jesus will suffice to cleanse us and cleanse us permanently. Permanent atonement requires blood from an everlasting God. A High Priest that has no beginning and no ending, after the order of Melchizedek, where the forerunner has entered for us, even Jesus, having become High Priest forever according to the order of Melchizedek (Heb 6:20).
Jesus, our permanent High Priest entered into the most holy place, not with the temporary blood of bulls and goats but with His own blood to obtain an eternal redemption for any who will trust Him. But Christ came as High Priest of the good things to come, with the greater and more perfect tabernacle not made with hands, that is, not of this creation. Not with the blood of goats and calves, but with His own blood He entered the Most Holy Place once for all, having obtained eternal redemption (Heb 9:11-12).
He entered the Most Holy place "once for all"; isn't that wonderful? It is done, finished. The work of salvation has been completed once and for all on the cross. All that is required of us is to enter into it with gratitude.