@Seabass I think you can look up the book you referenced yourself. It is not "a warning about the upcoming council," but a screed against the Jews. It might be correct in many of its facts, but I am not sure what it has to do with the council, although it was supposed to have been written anonymously by anti-council clerics. Maybe John XXIII said some favorable things about them, he did alter the Latin Mass to remove the reference to the "perfidious Jews." Also in the council documents, some positive things are said about the Jews. But the book is a history of (alleged?) Jewish conspiracies against the Church. I think the book says Arius was a converted Jew, that's an interesting tidbit that I never heard before, do not know if it's true or not, could be, but life is short and I do not have time to verify every fact. By the way, Saint John of the Cross and St Teresa of Avila were from Jewish families which had converted to Catholicism.