Wouldn’t one presentation appease the Father? If you are Augustinian-neo-Thomistic, you could say it was all one act of sacrifice (that is, Calvary, and all the Masses). If you are a modern Molinist you couldn’t say that because it is up to the priests’ free will, not God’s grace, which determines whether the Masses are to be said. Therefore they would say God was appeased by Good Friday alone.
So how does a Molinist explain offering a Mass, say, ten times for a person? Its hard to explain. A Protestant may simply never understand it. It makes vague sense to me.
If you are confused by what I’m saying about free will, read up on Controversies on Grace in the Old Catholic Encyclopedia
I’m not quite sure I fully understand your argument here. You insist that there is a difference between the Augustinian case and the Molinist case, but I’m not sure how you get there. So allow me to hypothesize about what your unlisted argument might be. Feel free to correct me if I am wrong.
Augustine essentially didn’t conceive of free will as most people today do. For him, mankind was born in a fallen state and doomed to damnation. They cannot help but choose to do evil, for which they are responsible for. However, the grace of God restores the elect’s true state, and thereby their free will is restored. In other words, free will itself is a form of grace. I would call this Augustinian free will.
Now if free will itself is a form of grace, then naturally multiple masses are nothing more than the participation of the grace of God in multiple forms.
In the Molinist case, or for anyone who believes in the more common understanding of free will (a Cartesian free will), multiple masses seems to be a strange thing indeed. If Christ’s one sacrifice was enough throughout all time, then why would anyone need to participate in more than one mass at all? It would seem to mean that Christ’s sacrifice was not enough then.
Here is my answer. I must admit upfront, I am adamantly opposed to Augustine’s conception of free will and grace. I don’t see multiple masses as an issue for Molinists. There are several answers, but perhaps the best and shortest one is as davidv has already said: repetition and whatnot might just be a means to alleviate our human weakness.
Alternatively, Augustine understood participation within the grace of God led to the pursuit of more grace so as to become ever-closer to God. I don’t see how this would be any different in the Molinist case. It is almost like another way of proclaiming theosis.
If you would like a longer answer, I suggest reading the works of Saint John Cassian.