|Above you see Fathers Ratzinger and Biali attentively listening to the comments of Fr. Karl Rahner, left, their mentor|
No, the post-conciliar theological principle is neo-modernism, and the theology that is based on it is known as the nouvelle theologie. It is the idea that old dogmas or beliefs must be retained, yet not the traditional 'formulas': dogmas must be expressed and interpreted in a new way in every age so as to meet the 'needs of modern man'.
This is still a denial of the traditional and common sense notion of truth as adaequatio intellectus et rei (insofar as it is still an attempt to make the terminology that expresses the faith correspond with our modern lifestyle) and consequently of the immutability of Catholic dogma, yet it is not as radical as modernism.
It is more subtle and much more deceptive than modernism because it claims that the faith must be retained; it is only the 'formulas' of faith that must be abandoned--they use the term 'formula' to distinguish the supposedly mutable words of our creeds, dogmas, etc. from their admittedly immutable meanings.
Therefore, neo-modernism can effectively slip under the radar of most pre-conciliar condemnations (except Humani generis, which condemns it directly) insofar as its practitioners claim that their new and unintelligible theological terminology really expresses the same faith of all times.
In other words, neo-modernism is supposed to be 'dynamic orthodoxy': supposedly orthodox in meaning, yet always changing in expression to adapt to modern life (cf. Franciscan University of Steubenville's mission statement).
Take extra ecclesiam nulla salus as a clear example of a dogma that has received a brutal neo-modernist re-interpretation: they claim that the old 'formula' that "there is no salvation outside the Church" must be abandoned; rather it is more meaningful to modern man to say that salvation is not in, but through, the Church; people who are not in the Church may still be saved through the Church; thus, to them the dogma that "there is no salvation outside the Church" means that there is salvation outside the Church. Hence see Ven. Pope Pius XII condemning those "reduce to a meaningless formula the necessity of belonging to the true Church in order to gain eternal salvation." (Humani generis 27).
(1) rampant in men like De Lubac, Von Balthasar, Congar, etc.: it is the ultimate goal of their writings, teachings, and activities as churchmen. To achieve this end, they employ the technique of 'resourcement', the neo-modernist strategy of fishing for the few dubious, questionable, or idiosyncratic teachings of some
Fathers of the Church and other authoritative writers, and gather them into a massive, heterodox theological argument against the traditional understanding of the faith (which they like to relativize by giving it names such as "Counter-Reformation" Theology, "Tridentine" Theology, or "Scholastic" Theology, instead of just admitting that it is Catholic Theology plain and simple). This technique accomplishes three things that go hand-in-hand:
(a) offers a refutation of traditional Catholicism,
(b) defends an interpretation that meets the needs of modern times, and
(c) gives it a semblance of being traditional, because it appears to be based in the Fathers et al. This type of argument is used, for example, by Von Balthasar in his nearly heretical book, Dare We Hope that All Men be Saved? to 'prove', not that Hell does not exist (that is a dogma), but that it is empty.
But this technique and its neo-modernistic underpinnings is not only practiced in almost all of these men's writings; it is also defended in theory by many of them, particularly in Von Balthasar's daring little book, Razing the Bastions, where he demonstrates that "Tridentine" theology must be rejected in our times because it is 'boring'.
(2) present in a more moderate way in the non-binding statements by post-conciliar popes, since they themselves were deeply involved in the developing of the nouvelle theologie. Just to give one of a million possible examples, see Pope Benedict's evolutionistic re-interpretation of the Resurrection of Our Lord.
Benedict XVI’s book,"Jesus of Nazareth":
“Therefore the Resurrection of Jesus is not an isolated event that we could set aside as something limited to the past, but constitutes an “evolutionary leap” (to draw ananalogy, albeit one that is easily misunderstood).” [page24]
Nothing obviously contradicts the dogma of the Resurrection (it may be interpreted as a simple analogy, even if a bad one, and nothing more), but it is a novelty that could be understood as claiming that the Resurrection is part of the natural development of nature, by using the word, "evolutionary" (thus giving credence to some of the nouvelle theologie's pet doctrines, such as De Lubac's heterodox notion of the supernatural and De Chardin's pantheistic evolutionism).
This happens almost on a daily basis in what comes out of the Vatican, not to mention what comes from local bishops.
(3) mostly implicitly or behind-the-scenes in the Council, the Catechism, etc., even though it seldom comes out more explicitly. Things are done at this level under the pretext of 'aggiornamento', a euphemism for neo-modernism. That is usually all the justification provided since at this authoritative level, there is no need to justify things theologically.
Hence, Vatican II and the Catechism are not outright neo-modernistic. Rather, they (like most of post-conciliar doctrine) tend in that direction and/or are inspired by that mentality.
In other words, most of the time these documents do not explicitly teach neo-modernist errors (the kind of errors you hear explicitly from neo-modernist theologians and priests).
Rather, they are full of dangerous ambiguities: statements that in a technical sense could be interpreted as being in harmony with the traditional faith, but that, in their natural, non-forced, interpretation are heterodox.
One clear example of this is Dignitatis humanae, par. 2; entire monographs have been written in order to prove that, despite appearances, this document does not contradict previous teaching. Maybe in fact it ultimately does not, but it is obvious that the prima facie meaning does; otherwise there would be no need to write so many volumes to prove it.
It must be noted that these are general tendencies, and that in some documents (cf. Gaudium et Spes) and every now and then in papal and episcopal statements neo-modernist principles rears come out more explicitly.