The key to understand that usage in scripture is that "blood" represents the life given in death. When God says without the shedding of blood there is no remission of sins He is not referring to a cut and a few drops of blood, but referring to the fact that in the sacrificial system He established in the garden of Eden and in Leviticus that the sacrifice must shed his blood until there is no life. The shedding of blood refers to the giving of ones life so that the sacrifice dies thus suffering typically the wages of sin which is death. That is the meaning of the "blood" of Christ as the antitype of the sacrifical system established by God so that the wages of death due to our sins has been satisfied by the giving of his life on the cross.
In the New Testament the use of "blood" as being "washed" or cleansed by the blood of Christ simply represents the consequences of the life of Christ sacrificed in our behalf. The forgiveness of sins, the imputed righteousness of Christ, etc. To have our conscience cleased by the "blood" of Christ simply refers to the fact that our guilt has been removed through faith in the sacrificial substitutionary gospel of Christ concerning His death burial and resurrection in our behalf.
Genesis 4:4
And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the LORD had respect unto Abel and to his offering:
Heb. 114 ¶
By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he was righteous, God testifying of his gifts: and by it he being dead yet speaketh.
There are five important facts that cannot possibly be denied here.
1. Neither Abel nor God borrowed this sacrifice from heathen as no heathen culture existed.
2. God accepted and approved of this "sacrifice" (Heb. 11:4) and "offering" (Gen. 4:4).
3. This sacrifice did not obtain but displayed the righteousness and faith of Abel and thus it was not a hypocritical act of worship which God despises.
4. This was an act of faith and faith is not blind but is obedience to God's revealed will. God himself killed animals previously to cloth Adam and Eve. New Testament writers refer to this initial sacrifice as typical in regard to Christ being the "lamb slain FROM the foundation of the world"
5. Here is the origin of shedding of blood in type as an act of faith in view of the coming promised "seed" (Gen. 3:15) who would shed his own blood for our sins.
