The word heresy (from the Greek haeresi) means choice, a choice made against or contrary to an established faith or practice. Within the context of church history, it means opinions that go contrary to God's revealed word. The word rationalism (from the Latin ratio) is defined as "a view that reason and experience rather than the nonrational are the fundamental criteria in the solution of problems." Rationalism seeks a natural as against a supernatural explanation. Within the realm of theology, E. J. Carnell expressed the essence of rationalism in his statement, "Bring on your revelations! Let them make peace with the law of contradiction and the facts of history, and they will deserve a rational man's assent" (An Introduction to Apologetics, 178). In this perspective, man's reason sits in judgment on God and his revelation instead of working in terms of it. Such rationalism may agree with orthodox theology, but in its basic premise, the sufficiency, right, and necessity of reason to sit in judgment over God and his revelation, it is heresy. It enthrones man's reason as the supreme judge over all things, beginning with God.
Rationalism has insisted on identifying itself with reason, a fallacy, because it represents a misuse of reason. Fallen man's original sin is to be his own god, knowing or determining for himself what is good or evil, right or wrong, or law or morality (Gen. 3:5). It can recognize and approve of the God of the Bible but only as an independent source of judgment and corroboration. Theological rationalism leads in time to humanistic rationalism. Its goal may be a kind of orthodoxy, but its methodology is simply a radical heresy. God created the heavens and the earth, and all things therein, including man and man's reason. The clay cannot judge the potter nor sit as a court to verify the potter's existence. Such a procedure is an absurd arrogance.
Cornelius Van Til repeatedly demonstrated the circularity of man's reason. Man begins on certain given premises to reason to their necessary conclusions. His thinking has a context. He does not approach any subject except from the given context of a given world. Still worse, the philosophers, most obviously the rationalists, refuse to deal with the fact of man's Fall and the effect of the Fall on man's mind. As Calvin noted, "Thus they imagine that man is always possessed of reason sufficient for the proper government of himself." (John Calvin: Institutes of the Christian Religion, Bk 1, chapt. XV, VI; vol. I, 213, Philadelphia, Pennsylvania: Presbyterian Board of Christian Education, 1936). Calvin continued, "The philosophers, being ignorant of the corruption of nature proceeding from the punishment of the fall, improperly confound two very different states of mankind" (ibid., Bk I, chapt. XV, VII; vol. I, 214). Salvation should not confirm man in the priority of his reason but rather make him mindful of its limitations and the sufficiency of God's revelation. Man's intellect, as Van Til pointed out, is not sinless. And when man ignores the Fall, it "is always tantamount to ignoring his creation" (Cornelius Van Til: An Introduction to Theology, vol I, 32. Philadelphia, Pennsylvania: Westminster Theological Seminary, Syllabus; 1947). As Van Til said further,
Nature has had a veil cast over it on account of the sin of man, and the mind of man itself has been corrupted by sin. Accordingly, use must not, now that sin has entered into the world, separate natural theology from the theological physics and theological psychology. After sin has entered the world, no one of himself knows nature aright, and no one knows the souls of man aright. How then could man reason from nature to nature's God and get anything but a distorted notion of God? The sort of natural theology that the sinner who does not recognize himself as a sinner makes is portrayed to us in the first chapter of Romans (ibid., 1, 69).
Some of the champions of rationalism will cite man's Fall in their theological statements, but not in their philosophies. There the subject is taboo, and their thinking assumes the unfallen purity of reason. How they can do this and still retain their orthodoxy they do not explain. But to disregard the Fall of man is to deny the Faith: it is heresy, not orthodoxy. Moreover, as Calvin pointed out, such men disregard God's predestination in their reasoning. As for the atonement, the subject never touches their philosophy! Calvin noted, "What God decrees, must necessarily come to pass; yet it is not by absolute or natural necessity" (Calvin, op. cit., Bk I, chapt XVI, IV, vol. I, 231). But the philosophers recognize only absolute or natural necessity, not God's decree, so that, even when they seem to agree with Biblical doctrine, they are totally at odds with it. The constructs of reason give us a god very much like man and the mind of man. To cite Calvin again, in a statement, like so many in Calvin ignored by these rationalists in the church, "Hence it happens that so many worthless characters in the present day violently oppose this doctrine, because they will admit nothing to be lawful for God, but what agrees with the dictates of their own reason" (Calvin, op. cit., Bk I, chapt. XVII, II; vol. I, 234). He added,
Therefore, since God claims a power unknown to us of governing the world, let this be to us the law of sobriety and modesty, to acquiesce in his supreme dominion, to account his will the only rule of righteousness, and most righteous cause of all things (Ibid, Bk I, chapt XVII, II; vol. I, 235).
Statements like this, which are many, are ignored by those philosophers who claim to be Calvinists; the man, the thinker in philosophy, is for them a creature who has never existed, not in Eden, nor in the world since. Their rationalism is a form of heresy, an attempt to combine humanistic philosophies and Biblical Faith. Not surprisingly, such rationalism has been especially prominent in Arminian circles, where the departure from the God of Scripture begins in theology. All the same, this heresy has been too common in Calvinistic circles.