Many therefore of his disciples, when they had heard this, said, This is a hard saying; who can hear it?
All Commentaries on John 6:60 Go To John 6
Theophilus of Antioch
AD 184
When you hear, however, of His disciples murmuring, understand not those really such, but rather some who, as far as their air and behavior went, seemed to be receiving instruction from Him. For among His disciples were some of the people, who were called such, because they stayed some time with His disciples.
Do not suppose from this that the body of Christ came down from heaven, as the heretics Marcion and Apollinarius say; but only that the Sonof God and the Son of man are one and the same.
The Evangelist wishes to show us, that He knew all things before the foundation of the world: which was a proof of His divinity.