[Claud]

Of course it's credible! Just read up on St Athanasius, Pope Liberius and the Arian heresy.

The Mass was invalid throughout the world in Liberius's time?

Even in that mess, was the Church at large entirely bereft of the Holy Sacrifice, as some are claiming today?

[piusv]

Our comments about the Arian heresy were not in response to your comments about a possibly invalid Mass. If you look back at what we quoted, we weren't referring to that there. We were referring to this quote of yours (and I'm pretty sure that ebbtide doesn't question the validity as I do):

Is it really credible that Christ would allow His Bride the Church to fall into such grave error that everyone from the Supreme Pontiff to the pewsitter is now manifestly outside it, save for a few straggling remnants, none of whom agree with each other?

If you take that quote by itself it absolutely describes the Arian heresy and how it affected much of the Church including the hierarchy including the pope to some degree. As for questions along the lines of "do you really think *this* (what ever that might be) could ever happen to the Church?", I'm willing to bet that Catholics during the Arian heresy and the Great Western Schism, for example, would have had similar questions because those things had never happened before.

The fact of the matter is, those *things* did happen even when most Catholics would never have thought them possible. So I'm not willing to sit around and assume that, just because certain circumstances never happened in the Church before, those circumstances can't possibly happen.

The bottom line is that despite these awful things, Christ never let the gates of Hell prevail (and never will).