NOTES for Luk 17:1-19
As the Savior's words show, the question of faith is directly connected with the question of spiritual life as such. What does it mean to increase faith? How did the disciples themselves understand an increase in faith? They must have meant something connected with the confidence they experienced when, at their Teacher's command, they preached the Kingdom and joyfully saw that not only people, but also spirits obeyed them. In those days, this sense of power was usually associated with faith, with its presence or absence. Jesus, however, is speaking of something somewhat different. He speaks of faith as a spiritual state. Precisely and only a spiritual one. After all, any manifestation of inner strength in a person is a natural phenomenon as much as a spiritual one. Here there is not only the spiritual impulse as such, not intention alone, but also nature and the psyche, which also respond to spiritual influence. But Jesus speaks only of the spirit. Only of the will. Only of intention.
Spirit is not nature. Quantitative measurements are impossible here. Spirit, or will, does not come in larger or smaller amounts. If the will is not fragmented, if it is not scattered through inner, psychological space or outer, physical space, it has absolute force. Not in the whole universe created by God, of course; only the will of the Creator Himself has that kind of power. But at one concrete point, it certainly does. That is why faith the size of a mustard seed is enough to move a mountain from its place. Faith here is not inner strength, and certainly not conviction about anything at all, but the fullness of relationship with God. It is that same fullness which, when directed toward creation, becomes the source of an infinitely powerful force, if only it is fully concentrated on something specific. But reaching that kind of concentration is not easy. No psychological techniques will help here.
This concentration is a derivative of that fullness of the life of the Kingdom which, in principle, has been opened after Christ's coming to everyone who seeks. It is the same fullness whose experience lets a person serve without counting merit: we have done what we were supposed to do; we are only servants who do not deserve a reward. It is the fullness in which one understands that every sin is absolutely destructive, and that, although sin is inevitable in the fallen world, complicity in it is always an existential catastrophe for a resident of the Kingdom. It is the fullness that is possible only in the Kingdom and without which there is no Kingdom. The fullness for which alone it makes sense to live.