“And I heard another voice from heaven, saying: Go out from her, my people; that you be not partakers of her sins, and that you receive not of her plagues. For her sins have reached unto heaven, and the Lord hath remembered her iniquities.”
From The Oratory Catechism:
727. May heretics be named in the Canon of the Mass?
No, anyone who names a heretic in the Canon of the Mass commits a sin and diminishes the grace effected by the Holy Mass.
Anyone who names a Pope or a Bishop in the Canon thereby shows his common faith with that person. Whoever knows that the person in question is a heretic and – in spite of this knowledge – calls him a Pope or Bishop is committing a mortal sin before God and contaminating the pure Sacrifice he is offering. Besides, he also cals his own credibility into question. Anyone who does not know for certain that the person with whom he is claiming a common faith is a heretic is also commtting a sin, since he has the duty to find out for sure in such a serious matter.
The Oratory Catechism: Roman Catholic Catechism and Instructions for the Faithful in Today’s World, Translation according to the Third Revised Edition, Foreword to the Second Edition by Fr. Paul Schoonbroodt, Foreword to the English Edition by Fr. James Baird, Published by the Oratory of the Divine Truth, SAKA-Verlag Saarbrücken. (First edition 1986, Foreword to the First Edition by Bp. Günther Storck.)