The idea seems to have gotten about in the last couple of centuries or so that “love” has triumphed over and abolished reason. Love conquers all. All you need is love. All that jazz about truth and justice . . . feh. It just gets in the way.
The problem is that, separated from a solid grounding in the natural virtues, principally justice, love isn’t really much of anything. Anything good, that is. It can actually turn into something very harmful. The late Msgr. Ronald Knox, for instance, defined “ultrasupernaturalism” or “enthusiasm” (not a good word in this context) as “an excess of love that threatens unity.” People who base everything on “love” all too often decide that others don’t love in the right way (or at all), and are therefore either ungodly or inhuman.
We cannot, however, cut love off from justice. Human positive law is based on the natural law, including the rights to life, liberty, and property, and the capacity to acquire and develop the virtues of prudence, temperance, fortitude, and, above all, justice. Human law is concerned with the task of becoming more fully human, that is, conforming to human nature by realizing our inherent capacity to acquire and develop the natural virtues.
The capacity for the supernatural law, faith, hope, and charity, is not natural to humanity, but is infused as a free gift. It is concerned with making us more fully adopted children of God.
Human law and divine law must not be in material conflict, but, on the other hand, are not to be merged, as each has its own directed end. Confusing these ends, or attempting to dismiss reason in favor of faith, is the principal error of “modernism,” the “synthesis of all heresies,” and operates to the detriment, as we have seen, of both civil society (the State) and religious society (the Church), and, increasingly, domestic society (the Family). It’s called “agnosticism” (Pascendi Dominici Gregis, § 6) and “Fideism” (ibid., § 7), e.g.,
“[T]he need of the divine, according to the principles of Fideism, excites in a soul with a propensity towards religion a certain special sentiment, without any previous advertence of the mind: and this sentiment possesses, implied within itself both as its own object and as its intrinsic cause, the reality of the divine, and in a way unites man with God. It is this sentiment to which Modernists give the name of faith, and this it is which they consider the beginning of religion.”
Every pope since Pius IX in 1846 has, in some way, condemned the idea that the supernatural law can supersede or replace the natural law, e.g., that charity can abolish or replace justice, or that faith can contradict reason. Pius XII identified this error as the most dangerous threat to Catholic doctrine in the modern world (Humani Generis, § 2).
The natural law applies to the entire human race. If the supernatural law is added to it, then it, ipso facto, no longer applies to anyone outside whatever religion has the power to coerce all others, thereby obviating free will and human dignity.
This is an issue that falls under the natural law, specifically justice and the right to life, not the supernatural law of faith, hope, and charity. The supernatural law may — and should — inspire and enlighten our conformity to the natural law, but it cannot replace it, nor is it, strictly speaking, essential to come to knowledge of God or of the natural law, which can be known by the force and light of human reason alone.