Luther’s well-known formulation, “Scripture and plain reason,” is the only basis on which we can properly ground true spiritual discernment. Discernment is the ability to understand, interpret, and apply truth skillfully. 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