“Liberalism…transgresses all commandments. To be more precise: in the doctrinal order, Liberalism strikes at the very foundations of faith; it is heresy radical and universal, because within it are comprehended all heresies…”
~ Fr. Felix Sarda y Salvany
Heresy, from an etymological standpoint, means nothing more than “to choose for oneself.” Obviously, then, the word is entirely appropriate for one who departs from orthodoxy to blaze his own trail. Heresy, then, implies the existence of orthodoxy, which is its counterpart. In the past, every heretic believed himself to be orthodox. The two terms are related to one another, in the same way that “to be inside” of something implies the existence of an “outside.” But with Liberalism something altogether new was introduced to man. It was a heresy, to be sure, but for the first time it was a heresy that made no pretenses at orthodoxy. It was, in fact, the first heresy to more or less explicitly reject orthodoxy as a valid conception. And because orthodoxy signifies those beliefs which are true, to render it invalid is to render incomprehensible the traditional notions about truth and error.
To quote again from Fr. Sarda:
[Liberalism] repudiates dogma altogether and substitutes opinion, whether that opinion be doctrinal or the negation of doctrine. Consequently, it denies every doctrine in particular. If we were to examine in detail all the doctrines or dogmas which, within the range of Liberalism, have been denied, we would find every Christian dogma in one way or another rejected—from the dogma of the Incarnation to that of Infallibility.
But Fr. Sarda will not leave his analysis incomplete. The explicit denial of the legitimacy of dogma carries with it an implicit affirmation of a “new dogma” which is both universal and negative in its character:
Nonetheless Liberalism is in itself dogmatic; and it is in the declaration of its own fundamental dogma, the absolute independence of the individual and the social reason, that it denies all Christian dogmas in general. Catholic dogma is the authoritative declaration of revealed truth—or a truth consequent upon Revelation—by its infallibly constituted exponent. This logically implies the obedient acceptance of the dogma on the part of the individual and of society. Liberalism refuses to acknowledge this rational obedience and denies the authority. It asserts the sovereignty of the individual and social reason and enthrones Rationalism in the seat of authority. It knows no dogma except the dogma of self-assertion. Hence it is heresy, fundamental and radical, the rebellion of the human intellect against God.
The victory of liberalism meant the extinction of the concepts of both heresy and orthodoxy, which really represented nothing more than the primordial duality of truth and falsity. The old positive-negative pair was then replaced with a single, universal negative which rendered the previous paradigm illegitimate and, further, assured that anyone indoctrinated into the negative dogma of liberalism would be completely unable to understand the old terms. Man was left to sit alone in the privacy of his home, asking with Pilate “What is truth?”
 Liberalism is a Sin, ch. 3.
 Liberalism is a Sin, ch. 3.
 John 18:38.