If anyone is willing to do His will, he will know of the teaching, whether it is of God or whether I speak from Myself. (7:17)
Throughout His ministry, Jesus was often asked to perform additional and unnecessary signs to prove His authenticity, as if it were open to honest question (cf. Matt. 16:1; John 2:18). Yet, He consistently denied such requests, because He knew that they came from hard-hearted unbelievers. No matter how many miracles He performed, the Lord understood that such people would refuse to believe.
Nonetheless, Jesus promised the person who honestly seeks the truth revealed by God, the one who is willing to do God’s will, that he will know the truth about Christ’s teaching, whether it is of God or whether it is not. The Lord’s challenge to the crowd was simple: If they would humble themselves before God’s Word (wherein His will is revealed) to know and obey it, they would come to a sure realization that His teaching was true. That challenge still stands two millennia later. The assurance promised in this verse is available to all genuine believers. Such confidence comes through the Holy Spirit, who confirms the truth about Christ to the willing heart (1 John 2:20, 27), both internally, through His testimony (1 Cor. 2:10–15; cf. Rom. 8:16), and externally, through manifestations that demonstrate the truth of the gospel (John 3:2; 5:36; 10:38; Acts 2:22).
Jesus’ challenge was bold, but it was not without precedent. Similar promises are given throughout the Old Testament. In the book of Deuteronomy, God promised Israel, “You will seek the Lord your God, and you will find Him if you search for Him with all your heart and all your soul” (Deut. 4:29). David counseled Solomon, “As for you, my son Solomon, know the God of your father, and serve Him with a whole heart and a willing mind; for the Lord searches all hearts, and understands every intent of the thoughts. If you seek Him, He will let you find Him; but if you forsake Him, He will reject you forever” (1 Chron. 28:9). In Psalm 119:2 the psalmist wrote, “How blessed are those who observe His testimonies, who seek Him with all their heart.” “You will seek Me and find Me,” God said through the prophet Jeremiah, “when you search for Me with all your heart” (Jer. 29:13).
The personification of wisdom in Proverbs 1:20–33 illustrates the clear-cut challenge Jesus made in this verse—one no false messiah would dare make. Those who heed wisdom’s call, who are willing to do God’s will, will receive further knowledge:
Wisdom shouts in the street,
She lifts her voice in the square;
At the head of the noisy streets she cries out;
At the entrance of the gates in the city she utters her sayings:
“How long, O naive ones, will you love being simple-minded?
And scoffers delight themselves in scoffing
And fools hate knowledge?
Turn to my reproof,
Behold, I will pour out my spirit on you;
I will make my words known to you.” (vv. 20–23)
But verses 24–33 reveal the fate of those who harden their hearts and are unwilling to turn to God:
Because I called and you refused,
I stretched out my hand and no one paid attention;
And you neglected all my counsel
And did not want my reproof;
I will also laugh at your calamity;
I will mock when your dread comes,
When your dread comes like a storm
And your calamity comes like a whirlwind,
When distress and anguish come upon you.
Then they will call on me, but I will not answer;
They will seek me diligently but they will not find me,
Because they hated knowledge
And did not choose the fear of the Lord.
They would not accept my counsel,
They spurned all my reproof.
So they shall eat of the fruit of their own way
And be satiated with their own devices.
For the waywardness of the naive will kill them,
And the complacency of fools will destroy them.
But he who listens to me shall live securely
And will be at ease from the dread of evil.
Accepting or rejecting the claims of Jesus Christ is never a purely intellectual decision; there are inescapable moral and spiritual implications that are also involved. Those who willingly seek and obey the truth will find it and will be set free from their slavery to ignorance and sin (John 8:32). But those who reject the truth prove themselves to be children of their “father the devil, [who] want to do the desires of [their] father. He was a murderer from the beginning, and does not stand in the truth because there is no truth in him” (v. 44). Unless they repent, they will share his fate.
17 The reason Jesus’ critics did not recognize that his teaching came from God was that they were not living in accordance with the will of God, evidenced most immediately by their desire to kill him in spite of Moses’ clear teaching against murder. Verse 17 states unambiguously that the person who chooses to do the will of God will in fact be able to discern that Jesus’ teaching does not come from him but from God. Only those who actually do the will of God are given the capacity to know this. There is no way of testing the validity of Jesus’ words from outside a relationship of faith. One must “taste” before “seeing” that the Lord is good (Ps 34:8). To know for certain that Jesus’ teaching comes from God one must be committed to doing what God desires. The inescapable requirement for understanding the claims of Jesus is faith. In a slightly broader sense, it is equally true that “the perception of truth depends on the practice of virtue” (cited in Ryle, 3:448–49).
7:17 If the Jews really wanted to know whether His message was true or not, it would be easy for them to find out. If anyone really wills to do God’s will, then God will reveal to him whether the teachings of Christ are divine or whether the Lord was simply teaching what He Himself wanted to teach. There is a wonderful promise here for everyone earnestly seeking the truth. If a person is sincere, and truly wants to know what is the truth, God will reveal it to him. “Obedience is the organ of spiritual knowledge.”
7:17 wills … shall know (Gk. ginōskō): Truth is imparted only to open hearts. God imparts the truth in accord with our ability to receive it (John 2:24, 25; 15:15–17; 16:4).
7:17 — “If anyone wants to do His will, he shall know concerning the doctrine, whether it is from God or whether I speak on My own authority.”
The best way to understand the Word of God is to decide to obey it, whatever it says. We put ourselves in great spiritual danger by trying to understand the Bible without first committing to obey God (Luke 12:47, 48).
 MacDonald, W. (1995). Believer’s Bible Commentary: Old and New Testaments. (A. Farstad, Ed.) (pp. 1509–1510). Nashville: Thomas Nelson.
 Stanley, C. F. (2005). The Charles F. Stanley life principles Bible: New King James Version (Jn 7:17). Nashville, TN: Nelson Bibles.