But there are some of you that believe not.
For Jesus knew from the beginning who they were that believed not, and who would betray him.
All Commentaries on John 6:64 Go To John 6
Cyril of Alexandria
AD 444
Herein again one may clearly see fulfilled that which was fore-heralded by one of the holy Prophets, With your hearing ye shall hear, and shall not understand, and looking shall look and shall not see. For the heart of this people is waxen fat, and they have weighed down their ears and closed their eyes, lest they should at all see with their eyes, and understand with their heart, and should convert, and I should heal them. For they being themselves ear-witnesses of the doctrines of the Saviour, and from none other of the saints learning them, but rather instructed in the mysteries by the Voice of the Lord of all, yea even seeing Him with their bodily eyes, waxed gross in their folly, and having closed the eyes of their understanding, turned them away from the Sun of Righteousness, not admitting the illumination of the gospel instruction. For evil were they, and guilty of many past offences. Wherefore also the wise Paul testified to us that hardness in part is happened unto Israel. But since it was the work of no common wisdom to acknowledge that He Who was veiled in human form is God, He saith that he cannot come to Him who has not yet received, i. e., understanding from God the Father, and with reason. For if every good gift and every perfect gift is from above and cometh down from the Father of lights, how much more will not the acknowledgement of Christ, be a gift of the Father's Eight Hand, and the apprehension of the truth how will it not be conceived to be beyond all grace? For in proportion as it is shewn to be the Giver of the highest goods, so much the more befits it that it depend upon the Divine Munificence. But not to the unclean does the Father grant the knowledge of Christ, nor to those accustomed to stray unto extravagant unbelief doth He infuse the most helpful grace of the Spirit: for not on mud is it right that the precious ointment be poured forth. And verily the blessed prophet Jeremiah commands that they be first purged by desire unto every good work, who desire to draw near unto Christ through faith, crying out, Seek ye God and when ye find Him call on Him; when He shall be nigh to you, let the ungodly man forsake his way, and the unrighteous man his counsel, and let him return unto the Lord, and He will have mercy upon him, for He will abundantly pardon your sins. Thou seest how he says that he must first depart from his old way, and remove from unlawful devices, that he may obtain remission of sins, i. e., through faith in Christ. For we are justified not by the works of the law, but by the grace that is from Him, and the forgiveness granted us from above.
But some one may say, Therefore what hindered Him from pardoning the Jews also, and from pouring out remission on Israel together with us? for this too would befit Him That was perfectly good. And how too (says he) will He speak truly when He saith to us, I came not to call the righteous, but sinners to repentance?
What shall we say then to these things? For them of Israel alone at the first was the grace of the Saviour devised. For He was sent, as Himself affirmed, only to the lost sheep of the house of Israel. And in truth they who will believe may yet attain unto life everlasting. But some, living in a nobler course of life, and searchers of the truth, received the grace of God the Father co-working with them unto salvation through faith and were saved: but the haughty Pharisee, and the hard-hearted high-priests with them, and the elders of the people, would not believe, though fore-instructed by Moses and the Prophets. But since through their own ill-counsel, they at length shewed themselves unworthy of everlasting life, they received not the illumination which is from God the Father. And you have the type of this too in the elder writings. For as to them who disbelieved God in the wilderness, entry into the land of promise was not given; so to these who by their unbelief dishonour Christ, entrance was not granted into the kingdom of heaven, whereof the land of promise was the type. And God is not unrighteous Who bringeth His wrath upon each. For He being Just by Nature, will discriminate altogether rightly, and will direct His Own Judgment agreeably to His Own Nature, even though we understand not the mode of the economy which is above us.
Profitably does the blessed Evangelist tell us that Jesus knew all things, and was not ignorant who should disbelieve, and who was the minister of impiety against Him, that He might again be conceived of as God, as knowing all things before they are.