Why must we believe God? Why should we take Him at His word? John Owen shows us here that the only reason we need to believe God is because, if He says it, it just simply is. His word is the only qualifier and to reject it, we are essentially calling Him a liar.
He doth not reveal himself by his word unto the principles of natural light, nor unto reason in its exercise; but yet these principles, and reason itself, with all the faculties of our ininds, are consequentially affected with that revelation, and are drawn forth in to their proper exercise by it. But in the gospel the ” righteousness of God is revealed from faith to faith,” Rom. i. 17,—not to natural light, sense, or reason, in the first place; and it is faith that is “the evidence of things not seen,” as revealed in the word, Heb. xi. 1. Unto this kind of revelation, ” Thus saith the Lord ” is the only ground and reason of our assent; and that assent is the assent, of faith, because it is resolved into testimony alone. – John Owen ( The Works of John Owen; Volume 4, page 85)