John Calvin Commentary John 6:30

"They said therefore unto him, What then doest thou for a sign, that we may see, and believe thee? what workest thou?" — John 6:30 (ASV)

What sign do you show? This wickedness abundantly proves how truly it is said elsewhere, This wicked generation seeketh a sign (Matthew 12:39). They had at first been drawn to Christ by their admiration of His miracles or signs, and afterwards, through amazement at a new sign, they acknowledged Christ to be the Messiah. With that conviction, they wished to make Him a king; but now they demand a sign from Him, as if He were a man unknown to them.

From where did such sudden forgetfulness come, except that they are ungrateful to God and, through their own malice, are blind to His power, which is before their eyes? Nor can it be doubted that they disdainfully treat all the miracles they had already beheld, because Christ does not comply with their wishes, and because they do not find Him to be what they imagined Him to be.

If He had given them an expectation of earthly happiness, He would have been highly applauded by them; they would undoubtedly have hailed Him as a Prophet, and the Messiah, and the Son of God. But now, because He blames them for being too much addicted to the flesh, they think that they ought not to listen to Him anymore.

And in the present day, how many are there who resemble them! At first, because they promise themselves that Christ will flatter their vices, they eagerly embrace the gospel and call for no proof of it. But when they are called to deny the flesh and to bear the cross, then they begin to renounce Christ and ask from where the gospel came. In short, as soon as Christ does not grant their prayers, He is no longer their Master.