I know there is nothing in the Word, or in the works of God that is repugnant to sound reason.

But there are some things in both, which are opposite to carnal reason; as well as above right reason. Therefore our reason never shows itself more unreasonable than in summoning those things to its bar which transcends its sphere and capacity.

There are hard texts in the works, as well as in the word of God. It becomes us modestly and humbly to reverence, but not to dogmatize too boldly and positively upon them. “When I thought to know this,” saith Asaph, “it was too wonderful me.” There was the arrogant attempt of reason. “I thought to know this”—there he pryed into the knowledge known only to Providence. “But it was too wonderful for me”—it was labor inutilis [useless labor], as Calvin expounds it. He pryed so far into that puzzling mystery of the afflictions of the righteous, and prosperity of the wicked, till it begat envy towards them, and despondency in himself (Ps 73:3, 13). And this was all he got by summoning providence to the bar of reason. Holy Job was guilty of this evil, and was ingenuously ashamed of it (Job 42:3).

Failing to apprehend the limitations of human reason place us in danger of:

1. Being drawn into an unworthy suspicion and distrust of the faithfulness of God in the promises.
Sarah laughed at the tidings of the son of promise, because reason contradicted and told her it was naturally impossible (Gen. 18:13, 14).

2. Being given to despondency of mind, and faintness of heart under afflictive providences.
When reason can discern no good fruits in our afflications, nor hold to the hope of deliverance from them, we are tempted to a sinful discouragement, saying, all these things are against us (1 Sam. 27:1).

3. Entertaining temptations to deliver ourselves by indirect and sinful mediums.
When our own reason fills us with a distrust of providence it naturally prompts us to sinful shifts, and there leaves us entangled in the snares of our own making (Is 30:15, 16).

Beware, therefore, you lean not too much to your own reason and understanding; nothing is more plausible, nothing more dangerous. In other matters it is appointed the arbiter and judge, we make it so here, and therefore we are so diffident and distrustful, notwithstanding the fullest security of the promises whilst our reason stands by unsatisfied.

—John Flavel
Adapted from The Whole Works of the Reverend John Flavel, 4:435–436.