Our caring and faith work exactly the same way as the motion of the heart that we call systole and diastole and the motion of the lungs that we call breathing. There is also a complete correspondence between these two motions and our will and understanding and therefore also our caring and faith, which is why will and its motivating feelings are meant by “the heart” in the Word, and understanding and its thinking by “the breath” in the Word and also by “the spirit.” So “breathing one’s last” is no longer living and “giving up the ghost” is no longer breathing.
It follows, then, that there can be no faith without caring or caring without faith, and that faith without caring is like the breathing of the lungs without a heart. This is impossible for any living creature; only an automation could do it. Caring without faith is like having a heart but no lungs, in which case we would have no awareness that we were alive. So caring does useful things by means of faith the way the heart accomplishes action by means of the lungs.
The likeness between “hearts” and caring on the one hand and “lungs” and faith on the other is so strong that in the spiritual world everyone can tell simply from people’s breathing what their faith is like and from their heartbeat what their caring is like. Angels and spirits live by heartbeat and breathing just as we do, which is why they feel, think, act, and talk as we do in the world.
from Life/Faith: Teaching for the New Jerusalem on Faith, Section 19