The shedding of blood is unnecessary for God to forgive sins. From Adam until Moses, no one had to kill animals to receive pardon.
“For until the law sin was in the world, but sin is not imputed when there is no law.” (Rom 5:13 NKJV)
So why did God establish the Law of Moses if He could simply not charge sin to our accounts?
Some think it’s because God wanted to dwell with Israel (Exodus 25:8) and cannot tolerate ANY sin in His presence.
We know, however, God appeared to sinful men like Cain without need for atonement first. In fact, Cain offered God a sacrifice He refused (Genesis 4:5), and still God offered Cain a path to redemption.
“If you do well, will you not be accepted? And if you do not do well, sin lies at the door. And its desire is for you, but you should rule over it.” (Gen 4:7)
Right after that Cain kills his brother, Abel.
The early church patriarch Irenaeus (circa 180 AD) offers the following perspective:
“[God] points out that it was not for this that He led them out of Egypt, that they might offer sacrifice to Him, but that, forgetting the idolatry of the Egyptians, they should be able to hear the voice of the Lord, which was to them salvation and glory.”
“They shall no more offer their sacrifices to demons, after whom they have played the harlot. This shall be a statute forever for them throughout their generations.” (Leviticus 17:7)
22 For I did not speak to your fathers, or command them in the day that I brought them out of the land of Egypt, concerning burnt offerings or sacrifices.
23 But this is what I commanded them, saying, ‘Obey My voice, and I will be your God, and you shall be My people. And walk in all the ways that I have commanded you, that it may be well with you.’
Here’s God explaining through His prophet Isaiah (chapter 43) that He can forgive sins without blood sacrifices:
23 You have not brought Me the sheep for your burnt offerings,
Nor have you honored Me with your sacrifices.
I have not caused you to serve with grain offerings,
Nor wearied you with incense.
24 You have bought Me no sweet cane with money,
Nor have you satisfied Me with the fat of your sacrifices;
But you have burdened Me with your sins,
You have wearied Me with your iniquities.
25 “I, even I, am He who blots out your transgressions for My own sake;
And I will not remember your sins.
26 Put Me in remembrance;
Let us contend together;
State your case, that you may be acquitted.
The LORD can acquit us of our sins for His “own sake”?!
So, then, why the need for blood in the New Covenant?
Foremost because blood is LIFE!!!
“But you shall not eat flesh with its life, that is, its blood.” (Genesis 9:4 NKJV)
“For the life of the flesh is in the blood, and I have given it to you upon the altar to make atonement for your souls….” (Leviticus 17:11)
“Then Jesus said to them, ‘Most assuredly, I say to you, unless you eat the flesh of the Son of Man and drink His blood, you have no life in you.’” (John 6:53)
Oh, but John, you forgot that we have been “propitiated” (super fancy theological term) by Christ’s blood (Rom 3:25; Heb 2:17; 1 John 2:2)! The Greek words the New Testament translates as “propitiation” (hilasmos, hilaskomai, and hilasterion) are translated consistently and many more times as “atonement”, “mercy” or “mercy seat” in the Greek Old Testament (Septuagint) including the passages for the Mosaic blood sacrifices. One of the primary meanings for atonement is “reconciliation” or at-one-ment (see Easton’s Bible Dictionary). The “mercy seat” is the place in the tabernacle where God physically dwelt (Lev 16:2).
“For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life.” (Romans 5:10)
Jesus didn’t change God’s ability to forgive (see Psalm 103). He changed our ability to OBEY!! He offered His life to ransom us (Acts 20:28; Eph 1:14) and liberates us from the power of sin (Rom 6:22), death (Rom 6:9), and the dominion of evil (Eph 1:19-23). Since we are endued with the Spirit of Christ (Rom 8:9), we can remain in covenant with Almighty God (John 15:5)!!
ASIDE: Why are the same words in Greek translated so differently between the testaments (NT: propitiate/appease; OT: atone/mercy)? Christians don’t really connect the OT to their faith in the same way as the NT. Readers have — and translators may share — certain theological expectations for the NT that just happen to find expression in Bibles that actually get sold.