The Lamb who was slain is a reference to Jesus Christ...He wasn't slain til 33 AD...Was it known he would be slain??? It was foreordained from the foundation of the World...
God's people in the OT received Manna to eat, to stay alive...For their spiritual redemption their priests offered the blood of animal sacrifices...The blood of Jesus was not an option at that time...But if it had been, why were the priests not aware of it and call down Jesus to handle the atonement which was present??? Why was it available for Catholics after 33 AD but for no one before that???
When Jacob wrestled Jesus, he made no mention of wrestling with someone who is going thru a crucifixion...Why did no one who actually had contact with Jesus back then recognia a lamb who had been slain???
Excellent point! Just as Jesus is the "Lamb who was slain from before the foundation of the world", so too are those who are the chosen in Him from before the foundation of the world - when looked at from the level of eternity. All these things happened once time began but even before that it was real in God's view. That is why the sacrifice was a once for all occurrence. We don't have to have it redone every time we sin against God and need a refill on sanctifying grace.
I fully understand why Catholics - especially those who are in charge of new converts - must defend the Catholic dogmas attached to the Eucharist and why it proves so futile to try to look at the subject from a different angle. It goes to the very heart of what Catholicism teaches about justification as well as their insistence for the need of NT priests to continually offer the "sacrifice of the Mass" and the exclusivity they claim to offer believers. I just hope that the light of the truth seeps into the hearts and minds of those who are seeking to know God with all their hearts.