It’s really a shame that sedevecantists and some trads make a negative judgement on Pope St. John XXIII, simply because he opened the Second Vatican Council. It was clear that his goal for the Council was to “present a clear doctrine able to enlighten the modern world in the state which it finds itself today,” and even wrote an Apostolic Exhortation of the praying of the Breviary “for success of the Second Ecumenical Vatican Council.”
One can have criticisms of the saintly Pope’s revisions to the Breviary and Mass in 1961 and 1962, respectively, but his autobiography paints a picture of a man wholly devoted to God and to the service of the Church. In his early life, as a seminarist, Angelo Roncalli seemed to have struggled with scrupulously, which abated as he aged and you can see the sense of peace he had in his older years. Pope St. John XXIII lived strictly according to the Imitation of Christ, having great humility and taking criticisms from others as truth. Most importantly, he was convinced of the necessity of obedience to the Church and his superiors, which can be seen from his Episcopal motto, Oboedientia et Pax.
“In the hour of farewell, or, better, of leave-taking, I repeat once more that what matters most in this life is: our blessed Jesus Christ, his holy Church, his Gospel, and in the Gospel above all else the Our Father according to the mind and heart of Jesus, and the truth and goodness of his Gospel, goodness which must be meek and kind, hardworking and patient, unconquerable and victorious.”
Pope St. John XXIII, ora pro nobis!