More importantly, Christianity literally turned some OT stories upside down. .... The lamb was clearly not killed to "atone" for any iniquities, as the Christians teach."The Church does not teach that the lamb was killed during Passover to atone for any iniquities.
What does the Church teach if not that Christ died for our iniquities and yet that he was the Passover Lamb?
"For Christ, our Passover lamb, has been sacrificed." [1 Cor. 5:7, NIV]
The first indication is by John the Baptist (John 1:29) who calls Jesus the lamb of God to take away the sins of the world.
That's a novel idea for Judaism, given that no sin offering could atone for the sins not yet committed.
The more important imagery is the lamb whose death and whose blood provided the seal of a covenant
The Torah is given as the ever-lasting covenant. That which is ever-lasting cannot be replaced or fulfilled. Also the New Covenant mentioned in Jeremiah is for the House of Judah and the House of Israel (in other words, for the Jews only), but it's still the Old Covenant except that it is written on the hearts so that no one needs to be taught to keep it.
Just as the Israelites ate the lamb as a seal of the old covenant, we too must eat the lamb of God (Jesus's body in the Eucharist) as the seal of the new covenant
Again, here we see almost identical beliefs in other religions, to wit: the Egyptians ate their man-god Osiris in a form of a wafer; he was also believed to have died and resurrected, and was announced by three wise men, the "messenger" star, etc.
The "upside down" of the OT practice is that the Passover lamb is not a Temple sacrifice, but is prepared in a household (like a Thanksgiving turkey), and not by a priest (i.e. it is not sacramental), and that Judaism does not condone human sacrifice! (cf Leviticus18:21, 24-25; Deuteronomy 18:10; Jeremiah 7:31, 19: 5; Ezekiel 23:37, 39).
Besides, Passover lamb was not a sin sacrifice; in other words, the lamb did not die because of Israel's sins (especially future ones!). Nowhere in the OT is any sacrifice seen as one that atones for sins in the future.
Also the Passover lamb's bones cannot be broken and the NT makes a comparison to Jesus' bones not being broken as a result, saying thereby scriptures are fulfilled [cf John 19:36; Ex 12:46].
But John's obvious cherry-picking leaves out, conveniently, that the same Exodus 12 says that the lamb must not be blemished, whereas Jesus is described in the Gospels as having been horribly "blemished" by Roman torture. How come some things in the scriptures apply and others don't?
Likewise, the same OT makes it clear that sin sacrifice had to be administered by a Jewish priest, not pagan soldiers. The blood of the sacrificed animal would be sprinkled on the altar and on the curtain by a Temple priest.