Interesting statement. It made me reflect.
I guess it seems to me that being infinite, there's no way God can't be involved in every aspect of every life.
So as far as intercession goes, the hard part for me is that sometimes the answer is no.
Faith, therefore, means believing that whatever the answer is, it's for the best - and then acting on it by continuing to do what you can.
After all, isn't that what this nurse did? Immersed in the essence of the horror of war, where all around her, in answer to screams of prayers, God was saying "no" - she rolled up her sleeves and went to work, with faith that somehow all was well.