The problem, however, is two-fold: First, the Pope must have uttered a truly manifest heresy, which requires denial of an article of divine and Catholic faith, such as the Trinity, not just any error against the teaching of the Church.
What on earth does this mean? "...not just
any error
against the teaching of the Church." No. It has to be a
special kind of error that meets with the approval of Mr. Ferrara.
I'll agree that a error against the nature of the Trinity would qualify, but why doesn't an error against the nature of the Church herself qualify?
Sedevacantists come to their conclusions based on the evidence while anti-sedevacantists simply change the argument whenever an argument is shown to be too weak to withstand scrutiny. Note that the declaration from many Conciliar prelates that Muslims and Catholics worship the same God (though the Muslim teachings about their god specifically
excludes Jesus Christ) though one is Trinitarian and the other is not. But, you see, that heresy against the Trinity does not pass the threshhold for Mr. Ferrara. (Please note that in this particular example, I'm not speaking of Benedict 16 as I'm not sure if he has actually made this argument. I am speaking, however, of all the bishops and cardinals that Ferrara would not accept as having excommunicated themselves.)