Church Fathers on Luke 17:5

The disciples hearing our Lord discoursing of certain arduous duties, such as poverty, and avoiding offenses, entreat Him to increase their faith, that so they might be able to follow poverty, (for nothing so prompts to a life of poverty as faith and hope in the Lord,) and through faith to guard against giving offenses. Therefore it is said, And the Apostles said to the Lord, Increase our faith.

That is, that the faith which has already been received in its beginning, might go on increasing more and more to perfection.

We may indeed understand that they asked for the increase of that faith by which men believe in the things which they see not; but there is further signified a faith in things, whereby not with the words only, but the things themselves present, we believe. And this shall be, when the Wisdom of God, by whom all things were made, shall reveal Himself openly to His saints face to face.