John 7:17

ἐάν τις θέλῃ. If any man willeth to do His will; see on John 1:44; John 6:67; John 8:44. The mere mechanical performance of God’s will is not enough; there must be an inclination towards Him, a wish to make our conduct agree with His will; and without this agreement Divine doctrine cannot be recognised as such. There must be a moral harmony between the teaching and the taught, and this harmony is in the first instance God’s gift (John 6:44-45), which each can accept or refuse at will. Comp. John 14:21. Doing the will of God means personal holiness, not mere belief: it is the ποιεῖν τὴν� of John 3:21.

γνώσεται. He will come to know, recognise; comp. John 7:26; John 8:32. No time is stated; but sooner or later the knowledge will come. ‘Will’ rather than ‘shall’; the words are partly a promise, partly a statement of fact. The test would be a strange one to men who were always seeking for ‘signs,’ i.e. miraculous proofs.

πότερον ἐκ τ. Θ. Whether it proceeds from God (as its Fount), or I speak from Myself. Note the change from ἐκ to ἀπό and comp. John 5:19; John 5:30; John 15:4.