Maybe it’s simply because sacrifice brings us into dealings with the unknown.
In the act of sacrifice, you establish a relation with something that you recognize as enigmatic and powerful. Our collective psyche seems to have lost touch with it, although science is providing countless motives for being overwhelmed by the unknown.The unknown itself is in our own mind as well—our mind is in its largest part totally unknown to us. Therefore, it is not only a relation to the exterior world, it is a relation to ourselves.
We establish a connection with the unknown through the act of giving something and, paradoxically, the act of destroying something. That is what is behind sacrifice. What you offer and what you destroy, it is that surplus which is life itself.
– Roberto Calasso
The Paris Review, The Art of Fiction no 217