A.T. Robertson Commentary John 6:45

"It is written in the prophets, And they shall all be taught of God. Every one that hath heard from the Father, and hath learned, cometh unto me." — John 6:45 (ASV)

Taught of God (διδακτο θεου). A free quotation from Isa 54:13 with this phrase in the LXX. There is here the ablative case θεου with the passive verbal adjective διδακτο (Robertson, Grammar, p. 516). In 1 Thessalonians 4:9 we have the compound verbal θεοδιδακτο. The same use of διδακτος with the ablative occurs in 1 Corinthians 2:13.

And hath learned (κα μαθων). Second aorist active participle of μανθανω. It is not enough to hear God's voice. He must heed it and learn it and do it. This is a voluntary response. This one inevitably comes to Christ.