Sacrifice appears in almost every religion throughout the world. It seems to stem from a human desire to "deserve" grace, salvation, redemption, what-have-you.
Remember that the Israelites had a pretty sweet gig going, until they demanded a king.
I can't imagine the true God, the one I believe I have been in contact with, would require, even desire, harmless animals being chopped up like a 4H mob movie. It sounds like what darkness would require or desire.
In the Old Testament, you have instances with hundreds of large animals - cows, bulls, and rams, being led to a crowded common area to be sacrificed. The panic that must have been in those animals, as they were being walked towards an alter, that would have been covered in pools warm blood. Animals who can be good at sensing danger, even before it is directly upon them. And with the smell of spilled blood thick in the nostrils, and the wailing cries of frightened animals, and the desperate moans of animals having their throats slashed, among the chaos of live animals waiting for the same. Blood that would spray out like a severed fire hose, coating everything around it in red, while the adrenaline filled animal hearts still pumped feverishly. The heaviness of death must have permeated throughout the crowd, with children present. And this spirit of death and fear is what God wants? Happy Birthday, God!
I was born with an instinct to not want to needlessly kill innocent animals, it's called not being a psychopath. Who sacrifices animals and even humans today? Satanists. And we're told that God needed a blood-bath to calm his nerves? Or he desperately needed to reconcile his sin balance sheet?