Since the heart is darkened, the rational mind no longer harmoniously aligns with the spiritual intellect of the heart. (Keep in mind that we do not use the word heart to mean emotion as it is often used in our culture.)
We have been created with the ability to reason, but since we have imperfect knowledge, spiritual illness, and disharmony in our relationship to God, we do not always use our reason rightly. In our condition of pride and delusion, we may use our reason to make arguments, sometimes long and complex, to justify our sin in our own minds and to convince other that we are right. The human being can justify terrible ideas and actions through logically consistent steps in reasoning that are based on dangerously false ideas.
However convincing our arguments may be, good-sounding rational arguments cannot really make evil actions good. Upon a foundation of basic assumptions, we can construct a series of strong opinions that together form the ideology by which we understand the world around us. If our foundational assumptions are false, the weak foundation renders the whole structure of our opinions unstable, not resting firmly on solid Truth.
Some basic assumptions about reality cannot be proved by reason alone, but are known to be true through revelation, that is, the spiritual knowledge revealed by the Uncreated One. We are sometimes too confident in our ability to determine what is true and good by using our own reason alone. We need the Light of spiritual insight to illumine the Way for the rational mind. Pride and delusion encourage overconfidence and cause us to complicate simple Truth.
Text copyright © 2017 by Fr. Symeon D. S. Kees