John Calvin Commentary John 11:15

"And I am glad for your sakes that I was not there, to the intent ye may believe; nevertheless let us go unto him." — John 11:15 (ASV)

And I rejoice, on your account, that I was not there. He means that His absence was profitable to them, because His power would have been less splendidly displayed if He had instantly given assistance to Lazarus. For the more closely the works of God approach the ordinary course of nature, the less highly they are valued, and the less splendidly their glory is displayed. This is what we experience daily; for if God immediately stretches out His hand, we do not perceive His assistance. Therefore, so that the resurrection of Lazarus might be acknowledged by the disciples to be truly a Divine work, it had to be delayed, so that it might be very far removed from a human remedy.

We should remember, however, what I previously observed, that the fatherly kindness of God towards us is here represented in the person of Christ. When God permits us to be overwhelmed with distresses, and to languish long under them, let us know that, in this way, He promotes our salvation. At such a time, no doubt, we groan and are perplexed and sorrowful, but the Lord rejoices for our benefit, and gives a twofold display of His kindness to us in this respect, that He not only pardons our sins, but gladly finds means of correcting them.

That you may believe. He does not mean that this was the first weak beginning of faith in them, but that it was a confirmation of faith already begun, though it was still extremely small and weak. Yet He indirectly suggests that, if the hand of God had not been openly displayed, they would not have believed.