Expositor's Bible Commentary Commentary John 6:29

"Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent." — John 6:29 (ASV)

The second question implies both desire and a sense of self-sufficiency. The people seemed sure that if they wished to do so, they were capable of doing the works of God (i.e., works that God requires of those who seek to please him). To Jewish questioners, obtaining eternal life consisted in finding the right formula for performing works to please God. Jesus directed them to the gift of God that could be obtained only by faith in him (cf. 4:10), contradicting directly the presuppositions of his interrogators.