It wasn't in a Catechism, to my knowledge. It was, however, a fairly standard answer Catholic theologians provided to account for the Catholic Eucharist (the sacrament was identical to Roman pagan sacraments and foreign to the earliest church practices).
If it isn’t in The Catechism of The Catholic Church, it isn’t Catholic “teaching”.
So we can correct your assertion, can’t we. It’s not Catholic teaching at all. We can call it, Myth Busted.
The meanderings of theologians do not equal the official teachings as stated by The Catholic Church in her Catechism.
In fact what I demonstrated from the Scripture, The Didache, and the Church Fathers shows a far more faithful sacrificial origin of the Eucharist.
Justin Martyr gives the outline of how the Eucharist was celebrated in his day. The Catholic Mass followed this same outline for 1850 years.
“But we, after we have thus washed him who has been convinced and has assented to our teaching, bring him to the place where those who are called brethren are assembled, in order that we may offer hearty prayers in common for ourselves and for the baptized [illuminated] person, and for all others in every place, that we may be counted worthy, now that we have learned the truth, by our works also to be found good citizens and keepers of the commandments, so that we may be saved with an everlasting salvation.
Having ended the prayers, we salute one another with a kiss. There is then brought to the president of the brethren bread and a cup of wine mixed with water; and he taking them, gives praise and glory to the Father of the universe, through the name of the Son and of the Holy Ghost, and offers thanks at considerable length for our being counted worthy to receive these things at His hands.
And when he has concluded the prayers and thanksgivings, all the people present express their assent by saying Amen. This word Amen answers in the Hebrew language to ge’noito [so be it].
And when the president has given thanks, and all the people have expressed their assent, those who are called by us deacons give to each of those present to partake of the bread and wine mixed with water over which the thanksgiving was pronounced, and to those who are absent they carry away a portion.” Justin Martyr. 155 Ad.
Catholics instantly recognise this as the Eucharistic celebration, simply because we have always followed the same formula.
Not only this we have the same understanding of the Eucharist after so much time has passed. The Eucharist is the flesh and blood of Jesus.
“And this food is called among us Eucharistia [the Eucharist], of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing that is for the remission of sins, and unto regeneration, and who is so living as Christ has enjoined.
For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Saviour, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh.” Justin Martyr .
The Didache and Justin martyr hold that the Eucharist is sacrificial and the fulfilment of the prophecy of Malachi.
Where in all this is the Roman paganism?