St. Robert would not say something so ridiculous as that Bergoglio is only a material heretic.

On what basis do you say that?
I must say, I get the impression that Pope Francis has the Faith but has chosen to serve the infernal master.
Can a satanist have the Faith? Can a satanist be Pope?
It is clear from the writings of St Robert that he believes it is up to a Council, even an imperfect one, to hold the Pope to account for errors in the Faith. Personally, I would not be surprised if such a Council failed to find him to be a formal heretic. I think he is very shrewd...

On what basis do you say that?
I must say, I get the impression that Pope Francis has the Faith but has chosen to serve the infernal master.
Can a satanist have the Faith? Can a satanist be Pope?

Intending to subvert the faith is intrinsically incompatible with possessing supernatural faith.  Why?  Because supernatural faith is not merely an act of the intellect, but is a combined act of will and intellect.  Supernatural truths cannot be grasped by the intellect along, but the will moves the intellect to submit to the authority of God Revealing.  So someone who intends to subvert the Faith cannot have supernatural faith.

So in theory it's possible for someone to believe 100% of what the Church teaches (the material faith) but not have the formal motive of faith, which requires believing these things based on submission of the will to the authority of God revealing through the Church.  I could even logically conclude that, yes, the Catholic Church is the True Church of Christ and that all of the Church's dogmas are true ... but refuse to make the submission of faith.

To give an example, there was a Jew whom Bishop Williamson knew (and invited to speak at STAS) who basically told the bishop that he believed that Jesus Christ was/is the Messiah, that the Catholic Church is the True Church, and that what the Catholic Church teaches is true.  So he was asked why he didn't convert to become a Catholic.  His answer was, "Because I don't have the faith."  This man had intellectually concluded the truth of the Catholic Church, and yet did not have the faith, where his will did not submit to it.  This was a very profound and eye-opening statement.