Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent.
29. The work of God is this. They had spoken of works Christ reminds them of one work, that is, faith; by which he means that all that men undertake without faith is vain and useless, but that faith alone is sufficient, because this alone does God require from us, that we believe For there is here an implied contrast between faith and the works...
Christ let them question Him freely, no small condescension. The wise teacher listens swiftly and turns even foolish questions toward what profits. These Galileans asking "What shall we do?" show a teachable mind, unlike the Judean critics who came only to cavil. He answers the sincere request, not the impertinent quibble.
AI summary
Commenting on John 6:28-59
They said therefore unto him,.... Seeing he proposed believing in him as the grand work of God to be done, and what is most acceptable in his sight: what sign showest thou then, that we may see and believe thee?