Like skilful physicians of the soul, men like Keach were experts at identifying and diagnosing the disease of sin in its several manifestations. A lost condition may present itself in a variety of ways. A loving doctor of the soul is careful to distinguish between what may be a mere ‘form of godliness’ and biblical godliness that possesses divine power and grace. When dealing with souls, this distinction demands the delicate use of the two great tools that are at every true Christian’s disposal, law and gospel.
Like Christ, the Great Physician, believers must apply these tools wisely. The law of God is like a scalpal, which must be precisely applied to those who may be guilty of presumption. It aims to expose sin and deal with the cancer of spiritual pride, which lies at the root of many spiritual ailments. One must seek to cut out this cancer.
However, the gospel is like a healing ointment that believers should apply to those wounded by God’s law.