And Jesus said unto them,
Because of your unbelief: for verily I say unto you, If you have faith as a grain of mustard seed, you shall say unto this mountain, Remove from here to yonder place; and it shall remove; and nothing shall be impossible unto you.
All Commentaries on Matthew 17:20 Go To Matthew 17
John Chrysostom
AD 407
The disciples seem to me to be in anxiety and fear that they had lost the grace with which they had been entrusted. For they had received power over unclean demons. So they approached him in private and asked him the question, not out of shame (for if the matter had got out and they were criticized, it would have been superfluous for the future to have been ashamed of admitting it in their words) but because what they were going to ask him was secret and of great moment. What, then, does Christ say? “Because of your little faith. For truly, I say to you, if you have faith as a grain of mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible to you.” But if you say “Where did they move a mountain?” I will say that they did things much greater than that in raising up innumerable dead. For moving a mountain and moving death from a body are not at all comparable. After them other saints, far inferior to the disciples, are said to have moved mountains when necessity demanded. It is clear that the disciples also would have done so had necessity demanded. But if there was never need at that time, do not find fault with them. The Gospel of Matthew, Homily