I bet if you read carefully and extensively and without a previously adopted agenda, you will find that it's not "a" propitiatory sacrifice but "THE" propitiatory sacrifice, that it is "one and the same" sacrifice as that made by Christ on the cross, once and for all and entirely sufficient, "sacramentally" re-presented (that is, made present, here and now), NOT repeated.
[Christ], our Lord and God, was once and for all to offer himself to God the Father by his death on the altar of the cross, to accomplish there an everlasting redemption. But because his priesthood was not to end with his death, at the Last Supper "on the night when he was betrayed," [he wanted] to leave to his beloved spouse the Church a visible sacrifice (as the nature of man demands) by which the bloody sacrifice which he was to accomplish once for all on the cross would be re-presented, its memory perpetuated until the end of the world, and its salutary power be applied to the forgiveness of the sins we daily commit.If I thought, as some seem to do, that the Catholic Church thought it was repeating Christ's sacrifice in the Mass, I never would have converted.
[From the Council of Trent, quoted in paragraph 1562 of the Catechism of the Catholic Church]
here
The priest offers the holy Sacrifice in persona Christi; this means more than offering "in the name of' or "in place of' Christ. In persona means in specific sacramental identification with "the eternal High Priest"(42) who is the author and principal subject of this sacrifice of His, a sacrifice in which, in truth, nobody can take His place."Today's sacrifice," the Greek Church stated centuries ago, "is like that offered once by the Only-begotten Incarnate Word; it is offered by Him (now as then), since it is one and the same sacrifice."
Thus, by virtue of the consecration, the species of bread and wine re-present (50) in a sacramental, unbloody manner the bloody propitiatory sacrifice offered by Him on the cross to His Father for the salvation of the world. Indeed, He alone, giving Himself as a propitiatory Victim in an act of supreme surrender and immolation, has reconciled humanity with the Father, solely through His sacrifice, "having cancelled the bond which stood against us."
(All emphasis added to make it easier to find the relevant words.)
You figure God loved His Son, Jesus??? You figure God was happy about the pain and humiliation??? You figure God suffered when Jesus, and because Jesus suffered???
You maybe think Jesus, when it was finally over, said to Himself; thank God, it is finally finished...And maybe God was saying, Hang on Son it's almost over, and finally, Son, it is finished...
You think God wants to keep Jesus on the cross until you guys are done with Him???
Jesus is NOT still on the Cross...And you can't put Him there...He will never be on a Cross again...
He is risen...
Jesus appeared to His disciples after He was raised...He was not on a cross...He said, I'm going away and will send the Comforter to take my place...
He DID NOT say, when you break bread and drink from the cup, I will climb back on the Cross...You figure that Jesus is in some sort of time warp so that for the last 2000 years He never left the cross???
Jesus died for me, but He is dying for you???
The argument that the sacrifice of the mass isn't a separate sacrifice but the same sacrifice perpetuated through time.
I submit that the sacrifice made on the cross was a historic space-time event which occurred once and can never be repeated. The application of the crucifixion goes on to our present day by the Holy Spirit convicting men of sin and the need to receive the benefit of the finished work done on the cross - forgiveness of their sin.
The sacrifice itself cannot be perpetuated. It was once-for-all -
"For we know that since Christ was raised from the dead, he cannot die again; death no longer has mastery over him. The death he died, he died to sin once for all; but the life he lives, he lives to God." Romans 6:9,10
The main theme of Hebrews is that there is no more sacrifice for sin whatsoever. Another theme is that there is also no need for a priesthood: Jesus was the perfect priest. And His work is done.
You said: If I thought, as some seem to do, that the Catholic Church thought it was repeating Christ's sacrifice in the Mass, I never would have converted.
Well, that's what the RCC teaches. It is a propitiatory sacrifice and it is repeated. Even employing the perpetuation of the same sacrifice isn't tenable given the Scriptures I've provided. I humbly suggest you re-read Hebrews.