An Informed Faith: The Position Papers of R.J. Rushdoony

The Bankruptcy of Rationalism

Rationalism claims to prove God by human reason, but the “god” it produces is only a product of fallen imagination—acceptable to man but not the living God of Scripture. By ignoring the Fall and its corruption of the human mind, rationalism assumes reason is neutral and pure, when in fact sin has radically warped man’s thinking. Because fallen man resists a God who judges him, he reshapes truth to fit his reason, making himself the final standard of knowledge. This shifts epistemology from God to man and replaces revelation with human judgment. Rationalism is thus not intellectual strength but evidence of the Fall at work. True knowledge begins with God’s revelation and Christ’s atonement, not autonomous reason. The long philosophical trail of rationalism has led not to certainty, but to confusion and despair—revealing its deep intellectual and spiritual bankruptcy.

Rationalism and Heresy

Rationalism becomes heresy when it places human reason in judgment over God’s revelation. By demanding that Scripture first satisfy the standards of fallen reason, rationalism enthrones man as judge and reduces God to an object needing validation. This repeats the original sin of Genesis 3:5—man seeking to be his own god. Scripture teaches that the Fall corrupted not only man’s will but also his mind. Reason is not neutral, nor capable of rightly judging God apart from submission to His Word. When rationalism ignores the Fall, predestination, and the atonement, it distorts theology even when it uses orthodox language. True faith does not deny reason but restores it to its proper place: serving God’s revelation, not ruling over it. To reject this order is not orthodoxy with a flaw—it is a fundamental departure from biblical Christianity.

Rationalism and the Mind of Man

Rationalism fails because it ignores the Fall. Scripture teaches that man’s original sin was the desire to be his own god, and as a result every part of his being—including his mind—is corrupted by sin. The Bible is explicit: “the carnal mind is enmity against God” (Rom. 8:7). Fallen reason is not neutral, nor capable of judging God rightly, because it refuses to submit to God’s law. Rationalism assumes that human reason can stand above God and evaluate His revelation, but this simply repeats the rebellion of Genesis 3:5. All thinking is shaped by moral presuppositions: either man begins with God in submission, or he begins with himself in defiance. There is no “pure” or autonomous reason. Today, rationalism has largely faded from secular philosophy but survives within the church, where Enlightenment assumptions still linger. By placing reason before revelation, it undermines biblical faith and denies the noetic effects of sin, turning theology into a subtle form of unbelief.

Descartes and Rationalism

Modern rationalism begins with René Descartes, whose famous claim “I think, therefore I am” made human self-consciousness the starting point of reality. Instead of God creating and defining all things, man’s thinking became the judge of what is real. God was reduced to an object that must be validated by human reason, laying the groundwork for the modern idea that God can be “created” or dismissed by man. This logic was developed further by Kant and Hegel, leading to the belief that the rational is the real. The result is a worldview in which man, not God, stands at the center, severed from the authority of the past, divine revelation, and moral consequence. Existentialism followed naturally, stressing the isolated moment and denying lasting meaning, accountability, or future hope. Cartesian rationalism ultimately collapses into irrationality, shrinking both theology and human life by exaggerating man’s powers. Christianity must reject this man-centered starting point and return to the Biblical foundation: God’s revelation, not human reason, is the source of truth, meaning, and reality.

Reason and Rationalism

Reason and rationalism are not the same. Reason is the God-given capacity to think, understand, and draw conclusions; rationalism makes human reason the final authority for truth, judging revelation instead of submitting to it. Christianity uses reason after faith—understanding the implications of God’s revealed truth—whereas rationalism demands that revelation first pass the test of human logic. Rationalism falsely treats man’s problem as intellectual rather than moral. Scripture teaches that all men already know God, but suppress that truth in unrighteousness (Rom. 1). The issue is not lack of evidence but rebellion. By replacing sin with “lack of knowledge,” rationalism undermines the gospel and opens the door to apostasy. True faith affirms reason under revelation, not revelation under reason. When reason is detached from God’s Word, it becomes irrational—and destructive to both theology and the church.