The reward of self-control is dispassion, and the reward of faith is spiritual knowledge.  Dispassion engenders discrimination, and spiritual knowledge engenders love for God. (Maximos the Confessor)

Those who know me best would probably agree (complain?) that I have considerable self-control.  This has not always resulted in dispassion.  By itself, self-control can inflame the passions as much as quiet them.

Maximos is almost certainly advocating apatheia (ἀπάθεια).  For the Stoics, writing five centuries before Maximos, apatheia is freedom from emotional disturbance.  It is a rational and ego-free reaction to external events.

Five centuries after Maximos, the great theologian of the Eastern Church Symeon wrote,

I affirm that dispassion (apatheia) consists not only in abstaining from the prompting of the passions, but in abandoning all desire for them, and even more, in divesting our mind from their fantasies.  Thus, if we so desire, we rise above the heavans, beyond all the visible and sensory, as if our senses were closed and our mind hand entered the super-sensible world, lifting the senses forcibly with it, like an eagle lifts its wings.

But the most finely tuned apatheia is insufficient and can be misleading. On my own, even at my most rational and courageous - perhaps especially then - I will choose poorly.  Dispassion must be wedded to love of God and neighbor.

Maximos tells us that spiritual knowledge is the reward of faith.  Is it also the essential substance of faith?