From scholar Richard Rubenstein's The Religion of Sacrifice and Abraham, Isaac and Jesus:
Judaism never entirely rejected the idea that God demands the sacrifice of the first-born son. However we evaluate the existence of child sacrifice in ancient Judah, Israel, Canaan, and the colonies of Canaan-Phoenicia, it is evident that we are dealing with a God who demands the death of children. In reflecting on the issue of child sacrifice in Judaism and Christianity, Levenson comments, “…the mythic-ritual complex that I have been calling ‘child sacrifice’ was never eradicated; it was only transformed."
A prime example of that transformation is the pidyon ha-ben ritual in fulfillment of the commandment already noted: “You shall redeem all the firstborn of your sons. None shall appear before Me empty-handed.” (Exodus 34:20) In this ceremony, the father presents his first-born son to a cohen or hereditary priest on the thirtieth day after his birth whereupon the priest asks the father, "Which do you prefer, your son or your money?" The father declares that he prefers his son and presents the cohen with five silver dollars, the symbolic equivalent of five biblical shekels, in order to "redeem" his son. The priest accepts the coins with the ritual formula, "This (the coins) in place of that (the child). This in exchange for that."
Read the whole thing. We Christians often refer to Christ as "the lamb of God;" "Lamb" because a "spotless lamb" was one of the ritual Jewish sacrifices of the time, used as a symbolic substitute for human sacrifice like Abraham's ram in the thicket.
Christians view the sacrifice of Christ - God's "son" - as the final and essential sacrifice needed to redeem a fallen mankind. Thus the ancient themes of blood and human sacrifice endure and give deadly serious substance to our worship today.
My August photo of the stone urns in Carthage which contained the ashes of firstborns sacrificed to Baal:
