DECEPTION.
The spurious character of the Isidorian decretals had been exposed by the Magdebur Centuriators, and no one with any knowledge of Christian antiquity could retain a doubt of their being a later fabrication. But the growth of the Papal system had been so inseparably associated with these forgeries, that the theologians of the Curia and the Jesuit Order were resolved to defend them and make further use of them for proving the infallibility and monarchy of the Popes.The Jesuit Turrianus composed an elaborate apology for the decretals. Bellarmine acknowledged that without the forgeries of the pseudo-Isidore, and of the later anonymous Dominican writers, it would be impossible to make out even a semblance of traditional evidence; the three leading authors of the new doctrine - St. Thomas, Cajetan, and Melchior Canus had grounded it exclusively on these fictions.
Bellarmine then made copious use of the Isidorian fictions.... But of course the most transparent fictions were welcome to him if they served the great end of supporting the universal monarchy of the Pope.... This dishonesty is shown again in his attempts to get rid of the fact he was perfectly acquainted with, that whole Church, with all universities and theologians of any weight in the sixteenth century, had rejected the Papal system in its two leading principles of absolute monarchy and infallibility......
This explains how it was that in the new edition of the Breviary a whole series of Popes of the first three centuries was introduced, with proper offices and lections, of whom no one knew anything, and who have left no trace behind them, who are found in none of the ancient martyrologies, and were taken no particular notice of in Rome for 1500 years.
The only ante-Nicene Popes in the ancient unreformed Breviaries ere Clement, Urban, Marcus, and Marcellus. But Bellarmine and Baronius introduced into the new Breviary, under Clement VIII., Popes Zephyrinus, Soter, Caius, Pius, Calixtus, Anacletus, Pontianus, and Evaristus, with lections taken from the pseudo-Isidorian decretals. And Cardinal Baronius, the author of the Annals, co-operated in this work, although he had there sopoken with indignation of the fraud of the pseudo-Isidore.
Citation for previous post is from the book
The Pope and the Council by Catholic historian Johann Joseph Ignaz Von Dollinger.
Quoting Dollinger doesn’t help your case.
Again, there is no proof of deception. Centuries later defenses by some Catholics only highlights the old age and acceptance the forgeries found - which in itself means the forgeries taught nothing of import that seemed odd or new.
The irony of using Dollinger probably won’t dawn on you. He died and was largely forgotten as a member of a schismatic and heretical sect which even he came to disagree with.