(30) Now are we sure that thou knowest all things.--Comp. John 16:19; John 16:23. The "now" is emphatic, as in the previous verse. They see in His present knowledge of their thoughts, and in the light which has come to them from the statements of John 16:28, the fulfilment of the promise which He has made for the future (John 16:23). They think that the day has already come when they shall ask Him nothing, for He knows all things, and communicates to them the fulness of truth.

By this we believe that thou camest forth from God.--They had believed this before (John 16:27), but here, as frequently, St. John remembers the development of their faith. (Comp. Note on John 2:11.) They find, in His knowledge of their thoughts (John 16:19), and in the full solution which He gives to their difficulties, ground for a new faith; and upon this new proof of His divinity they have a new faith in Him. (Comp. the instance of Nathanael's faith at the end of John 1)

Verse 30. - Now know we that thou knowest all things. He had answered their unutterable yearning. That which stirred them very deeply on many occasions was this proof that nothing in their hearts was hidden from him. Nathanael was one of them, and now he saw "angels of God ascending and descending on the Son of man." "Thou knowest all things." The idea in their minds does not embrace the full range of human inquiry, nor the depths of Deity, but all the things which are in their hearts to ask him. Their word is true even if in their intention they fall short of ascribing omniscience to their Lord. And thou hast no need that any one should put to thee these inquiries. Thou hast sounded the depths of our hearts, and found out the unutterable and unuttered within us. When we were afraid to ask thee concerning "the little while," thou didst discern our unspoken yearning, and now thou art so establishing thy Divine claim upon our reverence and affection, that we can trust thee to give us all needful illumination when we most require it. In this fact, in this consideration just stated, we find our justification and the cause of our faith. We believe that thou earnest forth from (ἀπό) God (ἀπό differs from the solemnity of the παρά or the ἐκ of Ver. 28. Though Lange makes the ὅτι equivalent to "because," yet generally John gives to the ὅτι which follows a verb after ἐν τούτῳ the sense of "that," thus introducing the object of the verb, though in one place, 1 John 4:13, both constructions are seen in the same sentence. The objective force of "that" is to be preferred here). We believe that thy whole ministry and message is a revelation of God, a coming near to us of the Father. Thy name is "Immanuel, God with us." A question arises whether the disciples in this gush of faith said more than they really meant, and deserved reproof, or whether they had reached an elevation of thought from which they never would absolutely recede.

16:28-33 Here is a plain declaration of Christ's coming from the Father, and his return to him. The Redeemer, in his entrance, was God manifest in the flesh, and in his departure was received up into glory. By this saying the disciples improved in knowledge. Also in faith; Now are we sure. Alas! they knew not their own weakness. The Divine nature did not desert the human nature, but supported it, and put comfort and value into Christ's sufferings. And while we have God's favourable presence, we are happy, and ought to be easy, though all the world forsake us. Peace in Christ is the only true peace, in him alone believers have it. Through him we have peace with God, and so in him we have peace in our own minds. We ought to be encouraged, because Christ has overcome the world before us. But while we think we stand, let us take heed lest we fall. We know not how we should act if brought into temptation; let us watch and pray without ceasing, that we may not be left to ourselves.Now are we sure that thou knowest all things,.... Not only all men, but all things, even the secrets of men's hearts, of which the apostles had now a convincing proof; for whereas Christ had delivered some expressions, John 16:16; which they did not understand, and were desirous to ask him the meaning of, John 16:19; which he knowing, being God omniscient, prevents their putting the question to him, and enters upon a discourse, in which he so clearly explained what they wanted to be informed of, without their asking him, that they were fully assured that he must know all things;

and, as they add,

needest not that any man should ask thee: the meaning is, that should Christ deliver anything not so intelligible to any of his audience, and they were desirous of knowing the sense of it, there would be no need of putting the question in form to him, since he is privy to the first motion of desire rising up in the mind; and can, and will, if he thinks fit, explain himself on such an head, to the satisfaction of the person, without ever asking him; at least there is no need of putting the question to make him acquainted with his desire, this being before known unto him. By this we believe that thou camest forth from God; was the true Messiah, and had his mission and commission from God, as such; doubtless they believed this before, but this instance of Christ's omniscience was a strengthening proof of it. So Nathanael, by Christ's saying to him, that before Philip called him, and when he was under the fig tree, he saw him when he thought no eye did but an omniscient one; it laid him under such full convictions of him, as at once to acknowledge him the Son of God, the King of Israel. This is one of the signs and characters of the Messiah with the Jews, that he should have a discerning spirit of men and things, according to Isaiah 11:3 (c).

(c) T. Bab. Sanhedrin, fol. 93. 2.