I have heard many well thought out explanations to this, and it all comes down to human sacrifice, believe it or not.
Consider the first sacrifice of Abraham. "God" replaced Isaac with a ram. The first recorded "replacement" sacrifice. (and one of the first instances of the prickishness of YHWH)
There are all kinds of theological arguements on Jephtha and his offering of the first one of his house to YHWH if he were granted victory.
(Judges
11:30-31) . . .Then Jeph´thah made a vow to Jehovah and said: "If you without fail give the sons of Am´mon into my hand, 31 it must also occur that the one coming out, who comes out of the doors of my house to meet me when I return in peace from the sons of Am´mon, must also become Jehovah’s, and I must offer that one up as a burnt offering." 11:30-31) . . .Then Jeph´thah made a vow to Jehovah and said: "If you without fail give the sons of Am´mon into my hand, 31 it must also occur that the one coming out, who comes out of the doors of my house to meet me when I return in peace from the sons of Am´mon, must also become Jehovah’s, and I must offer that one up as a burnt offering.".......until it was his daughter who came out. Why else would he be that upset when she came out to greet him?
Of course, their is JW spin, there always is, but it takes several jumps. Clearly, Israel did get involved with some kind of human sacrifice, whether in imitation of the lands around them or otherwise.
How were the Israelite religious leaders to seperate themselves, while keeping the concept of a human sacrifice viable? Animal sacrifice.
Of course, for all of Jehovah/YHWH's hatred of offering human sacrifice's as he stated.......
(Deuteronomy
18:10)10 There should not be found in you anyone who makes his son or his daughter pass through the fire, anyone who employs divination, a practicer of magic or anyone who looks for omens or a sorcerer,He still (allegedly) showed his great love by offering the only approved human sacrifice, his own son.
I guess its ok to kill your own kid as long as they aren't burned in the process. Thus, Jesus was "sacrificed". Even though humans are forbidden to do that. Way to set an example....
The point is, human and animal sacrifice are found throughout ancient religious traditions, as they spill blood to appease the gods. IN ALL CASES, ITS ABOUT BLOOD BEING SHED TO APPEASE AND CALM DOWN THE DEITY. It was to remind you that the animal DIED IN YOUR PLACE. God had a right to kill you, and something has to be killed, because you sinned. Better an animal then you! How loving of YHWH.
Jehovah/YHWH was no different then the pagan gods around Israel. He was a blood thirsty god, as is evidenced by his surrogates, the priests.
These sacrifices served their purpose, to maintain control over the multitudes who bought that there was an invisbible god who would only forgive and accept if blood was poured out. Animal blood or your own? An easy choice for Israelites.