When Martin Luther was summoned to the Diet of Worms in 1521 and asked to recant his teaching, he replied, "Unless I am convinced by Scripture and plain reason, my conscience is captive to the Word of God. I cannot and I will not recant anything, for to go against conscience would be neither right nor safe. God help me. Here I stand, I can do no other."
Luther's well-known formulation, "Scripture and plain reason," is the only basis on which we can properly ground true spiritual discernment.
Scripture isn't antithetical to sound, rational wisdom, though many today imagine otherwise. Reason is no substitute for Scripture, of course, but when good reason and sound logic are kept subject to the authority of Scripture, they are in no way a threat to the truth. On the contrary, the application of sound, logical thinking to the truth of Scripture is a key aspect of the formula for discernment.
Contrary to what a lot of people these days assume, discernment is not a mystical or intuitive ability to know the truth as if by magic. It is the skill of understanding, interpreting, and applying truth accurately. Discernment is a cognitive act. Therefore no one who spurns right doctrine or sound reason can be truly discerning.
Authentic spiritual discernment must begin with Scripture-revealed truth. Without a firm grounding in divine revelation, human reason always degenerates into skepticism (a denial that anything can be known for certain), rationalism (the theory that reason is a source of truth), secularism (an approach to life that purposely excludes God), or any number of other anti-Christian philosophies.
When Scripture condemns human wisdom (1 Cor. 3:19), it is not denouncing logic and reason per se, but humanistic ideology divorced from the divinely-revealed truth of God's Word. In other words, reason apart from the Word of God leads inevitably to unsound ideas, but reason subjected to the Word of God is at the heart of wise spiritual discernment.