John Calvin Commentary John 6:14

"When therefore the people saw the sign which he did, they said, This is of a truth the prophet that cometh into the world." — John 6:14 (ASV)

Those men, therefore. The miracle appears to have had this advantage: they acknowledge its author to be the Messiah; for Christ had no other purpose. But immediately they apply the knowledge they have obtained concerning Christ to a different and improper purpose. And it is an extremely common fault among people to corrupt and pervert his truth by their falsehoods as soon as he has revealed himself to them; and even when they appear to have entered the right path, they immediately fall away.