John Calvin Commentary John 9:28

"And they reviled him, and said, Thou art his disciple; but we are disciples of Moses." — John 9:28 (ASV)

Then they upbraided him. It is probable that all the reproaches, fueled by their violent rage and indignation, were eagerly hurled at him. But one particular reproach was that they called him an apostate from the Law. For, in their opinion, he could not be a disciple of Christ without rejecting the Law of Moses, and they explicitly portrayed these two things as inconsistent with each other.

It is a very plausible pretense that they are afraid of rejecting the doctrine of Moses. For this is the true rule of piety: we should listen to the prophets, through whom we know for certain that God has spoken, so that our faith is not swayed by any human doctrines.

From this principle they deduce their certainty regarding the Law of Moses; but they lie when they say that they are the disciples of Moses, for they have strayed from the purpose of the Law. Thus, hypocrites are accustomed to tear God’s truth to pieces when they wish to take refuge under His name.

If Christ is the soul of the Law, as Paul tells us (Romans 10:4), what will the Law be when separated from Him but a dead body? We are taught by this example that no one truly hears God unless they are an attentive hearer of His word, in order to understand what God means and says.