“Was not Christ once for all offered up in His own person as a sacrifice? And yet, is He not likewise offered up in the sacrament as a sacrifice, not only in the special solemnities of Easter, but also daily among our congregations; so that the man who, being questioned, answers that He is offered as a sacrifice in that ordinance, declares what is strictly true? For if sacraments had not some points of real resemblance to the things of which they are the sacraments, they would not be sacraments at all” -St. Augustine of Hippo
“The question is posed, whether what the priest does is properly called “sacrifice” or “offering” (immolatio), and whether Christ is offered (immoletur) daily, or was offered only once. The answer can be made briefly, that that which is offered and consecrated by the priest is called sacrifice and offering (oblatio), because it is the memory and representation of the true sacrifice and holy offering (immolatio) made on the altar of the Cross.
And Christ died once on the Cross, and there was offered (immolatus) in Himself; but daily He is offered in the Sacrament, because in the Sacrament, there takes place the remembrance of what was done once...… what is done on the altar is and is called a sacrifice; and Christ was offered once, and is offered daily, but in one manner then, in another now.” -Peter Lombard
Catholics like to have their cake and eat it too.
It’s another one of those situations where say something out of both sides of their mouth so no matter what a non-Catholic says, they can always tell them they’re wrong.