Well, they must have the power to sustain themselves from somewhere, no? The energy required for an act of god to take place does not come from nowhere; if not from the worshippers, then they drink deep of the aether of the land.

[An oddity that she might notice, paying attention, is that as he speaks, while the word 'aether' is foreign, there is no doubt to what it means, both magical energy and life energy, the two effectively synonymous.]

There is a continent in the southern part of the Source called Meracydia which still today bears the scars of warring gods from three millennia ago. Little grows there save in isolated regions; much of it is a wasteland, uninhabitable.