By Rationalism is meant the system or theory which assigns undue authority to reason in matters of religion. By reason is not to be understood the Logos as revealed in man, as held by some of the Fathers, and by Cousin and other modern philosophers, nor the intuitional faculty as distinguished from the understanding or the discursive faculty. The word is taken in its ordinary sense for the cognitive faculty, that which perceives, compares, judges, and infers.
The Christian Church confesses on the one hand that God is the Incomprehensible One, but also on the other hand, that He can be known and that knowledge of Him is an absolute requisite unto salvation.
Jehovah, who shall sojourn in thy tabernacle?
Who shall dwell in thy holy hill?
2 He that walketh uprightly, and worketh righteousness,
And speaketh truth in his heart;—Psalm 15:1-2. (1901 ASV)