I really liked the whole Cishaurim thing and I think it is a bit of shame their sorcery / philosophy / metaphysics was not explored a little further.
Since there is a clear analogy between Fanimry and one particular monotheistic religion, what would people think if the Cishaurim are like super awesome Sufi monks.
The closer they come to the Solitary God, through acts of transcendence, be it fasting, meditation on the nature of the Solitary God, crazy swirling dancing and so on, the more power they can summon / channel.
I am not big fan of the dichotomy intellect vs religion. Religion under the right conditions is a non scientific way of making sense and explaining a world which defies explanation. Look at the Dunyain or the Inchies for that matter, how depraved their quest for the Absolute (or Salvation) has made them.
Whereas from the little we have seen the Cishaurim are more at ease with themselves. Of course this could not be the case, but there is little else in the text to go by.