John 7:17 - Ellicott's Commentary On The Whole Bible

If any man will do his will, he shall know of the doctrine. — Better, If any man willeth to do His will, he shall know of the teaching. The stress is upon “willeth,” which in our version reads as if it were only the auxiliary verb. It is not deed, which is the outcome of faith; but will, which precedes it, that is here spoken of. This human will to do the divine will is the condition of knowing it. The words are unlimited and far-reaching in their meaning. Those who heard them would naturally understand them, as it was intended they should, of the divine will expressed in the Law and the Prophets (John 7:19), but they include the will of God revealed, more or less clearly, to all men and in all times. Our thoughts dwell naturally on representative lives, such as those of Saul the Pharisee, Cornelius the centurion, Justin the philosopher; but the truth holds good for every honest heart in every walk of life. The “any man” of Christ’s own words excludes none from its reach, and the voice of comfort and of hope is spoken alike to all in our ignorance, fears, doubts — that he who in very deed willeth to do God’s will, shall not fail to know, now or in the life to come, of the teaching whether it be of God. (Comp. Notes on John 5:44 et seq., and John 6:29 and John 6:45.)