A.T. Robertson Commentary John 6:65

"And he said, For this cause have I said unto you, that no man can come unto me, except it be given unto him of the Father." — John 6:65 (ASV)

Except it be given him of the Father (εαν μη η δεδομενον αυτω εκ του πατρος). Condition of third class with εαν μη and periphrastic perfect passive subjunctive of διδωμ. Precisely the same point as in verse 44 where we have ελκυση instead of η δεδομενον. The impulse to faith comes from God. Jesus does not expect all to believe and seems to imply that Judas did not truly believe.