There are those within and faithfully obedient to the Catholic Church who feel that Vatican II was a serious rupture with the traditional teaching of the Church and must be repudiated.
As a convert, I have been studying this discussion and the relevant documents for several years and while deeply appreciating the feeling about the rupture, I have come to understand that Vatican II was a continuity of belief and doctrinal development within the history of the Church in the world.
The source that can help one understand this is the Catechism which grew out of Vatican II, the Catechism of the Catholic Church, and though I prefer some of the language—especially concerning capital punishment—from the first edition, the second edition is the accepted version; and I encourage all to read and study it as it is a marvelous document, and will resolve many of your concerns about Vatican II, if you have them.
This article from Chiesa examines the turmoil around Vatican II—in a discussion of the works of Romano Amerio—whose book Iota Unum is a must read.
“ROME, July 12, 2010 – For a few days a new volume by Romano Amerio has been in Italian bookstores, the third of the author's "opera omnia" being published by Lindau.
“Amerio, who died in 1997 at the age of 92 in Lugano, Switzerland, was one of the greatest Christian intellectuals of the twentieth century.
“A philologist and philosopher of the first rank, Amerio became known all over the world for his book first published in 1985 and translated into multiple languages, entitled: "Iota Unum: A Study of Changes in the Catholic Church in the Twentieth Century."
“But this same book, precisely because of the ideas supported in it, got Amerio ostracized by almost the entirety of the Catholic world. An ostracism that has been lifted only recently, thanks in part to the republication of "Iota Unum."
“Amerio dedicated half a century to writing "Iota Unum." And this third volume of the "opera omnia" was written over a much longer span, from 1935 to 1996. It is entitled "Zibaldone," and – like the work of the same name by the poet Giacomo Leopardi – it is a collection of brief thoughts, aphorisms, stories, citations from classics, moral dialogues, commentaries on events of the day.
"With its more than seven hundred thoughts, "Zibaldone" is a sort of intellectual autobiography. In which the questions raised in "Iota Unum" are naturally present.
“Like, for example, in this entry dated May 2, 1995:
"The self-demolition of the Church deplored by Paul VI in the famous speech at the Lombard Seminary on September 11, 1974, is becoming clearer by the day. Even during the council itself, Cardinal Heenan (Primate of England) complained that the bishops had ceased exercising the office of the magisterium, but comforted himself with the observation that this office was fully preserved in the Roman pontificate. The observation was and is false. Today the episcopal magisterium has ceased, and that of the pope as well. Today the magisterium is exercised by theologians who have shaped all of the opinions of the Christian people, and have disqualified the dogma of the faith. I heard an astonishing demonstration of this while listening to the theologian of Radio Maria last night. With boldness and great tranquility, he denied articles of the faith. He taught [...] that the pagans to whom the Gospel is not proclaimed, if they follow the dictates of natural justice and try to seek God with sincerity, will go to the beatific vision. This modern doctrine goes back to the ancient Church, but it was always condemned as error. But the ancient theologians, while they held firm the dogma of the faith, nevertheless felt all of the difficulty that dogma encounters, and tried to overcome it with profound thinking. The modern theologians, however, do not perceive the intrinsic difficulties of dogma, but run straight to the 'lectio facilior,' sweeping all the doctrinal decrees of the magisterium under the rug. And they do not realize that by doing this they negate the value of baptism and the entire supernatural order, our whole religion. Rejection of the magisterium is widespread on other points as well. Hell, the immortality of the soul, the resurrection of the body, the immutability of God, the historicity of Christ, the unlawfulness of sodomy, the sacred and indissoluble nature of matrimony, the natural law, the primacy of the divine are other arguments in which the magisterium of the theologians has eliminated the magisterium of the Church. This arrogance of the theologians is the most visible phenomenon of self-demolition."
“From this strongly critical analysis, which he also applied to Vatican Council II, Amerio drew out what Enrico Maria Radaelli, his faithful disciple and editor of the publication of his master's works, calls the "great dilemma at the heart of Christianity today."
“The dilemma is whether there has been continuity or rupture in the magisterium of the Church before and after Vatican II.”