John Calvin Commentary John 16:31

"Jesus answered them, Do ye now believe?" — John 16:31 (ASV)

Do you now believe? As the disciples were too highly pleased with themselves, Christ reminds them that, remembering their weakness, they should instead keep themselves within their own limited capacity. Now, we are never fully aware of what we lack, and of our great distance from the fullness of faith, until we come to some serious trial; for then reality shows how weak our faith was, which we imagined to be full. Christ recalls the disciples' attention to this matter and declares that they will soon forsake him; for persecution is a touchstone to test faith, and when its weakness becomes evident, those who were formerly swelled with pride begin to tremble and to draw back.

The question asked by Christ is therefore ironical, as if he had said, “Do you boast as if you were full of faith? But the trial is near, which will disclose your emptiness.” In this manner, we should restrain our foolish confidence when it indulges itself too freely. But it might be thought either that the disciples had no faith at all, or that it was extinguished when they had forsaken Christ and were scattered in all directions. I reply, though their faith was weakened and had almost given way, still something was left from which fresh branches might afterwards spring forth.