The Church has no official statements about probability one way or another. There are certainly Catholics who think that the probability of their beliefs is one (which is insane), but typically they do not hold this by saying that no possible evidence would convince them. They say, "such and such would convince me that Catholicism is false, but such and such is absolutely impossible, and I am absolutely certain that it is absolutely impossible."
On the other hand there are many far more reasonable Catholics who admit that their probability is less than one, admit that there is evidence that would convince them their beliefs are false, and admit that they might later observe the evidence. The Church has never said anything against such opinions (or against the first kind of opinion).
One person I know, whom pretty much everyone considers to be a devout and orthodox Catholic, told me that he would be happy with a probability of 30% (that is, he would be happy to believe with that probability, based on Pascal's wager type reasoning). I suspect that in practice his personal probability is around 50%.
The discussion about probabilities was all concerning the following specific question: How should we interpret the language in, e.g., Humani Generis about how faithful Catholics are required not to hold that some things are definitely true but the RCC teaches that some other things are definitely true? For sure, no translation into LW-style probabilityese is going to reproduce the meaning exactly, but one might reasonably hope to approximate what the RC documents say in terms that make some kind of sense to rationalists.
Another month, another rationality quotes thread. The rules are: