A useful formula in connection with Faith is the well-known "Ohms Law"
Amount = Pressure / Resistance
This shows in the simplest ways the relative factors concerned. The obtain a given amount of faith we must either increase pressure, decrease resistance, or both. It might appear that resistance should be removed altogether, but this would be highly unwise. A proportion of resistance is strictly necessary in order to maintain balance. We are all too familiar with what happens in the case of those who believe unrestrictedly and indiscriminately in anything. Fanaticism, insanity, and all kinds of stupidities arise from blind credulity and unreasoning enthusiasms coming from usually sincere but quite unjustified faith. Belief must always be qualified by discrimination in order to obtain good results. Another way of expressing the formula is
I will / I won't = I might
In other words what might happen is the outcome of Will over Won't.
So while Faith is a vital necessity, it must be effectively controlled with Wisdom if it is to be a practical proposition in working the Mysteries well. The position may be crudely but soundly summed up in the ale-house adage: "In God we trust - All others, cash!" We can only afford unreserved, complete and unresisting Faith in the Supreme Spirit Itself.
In Mystery practice, Initiates are taught to use belief with discrimination. This means specification of faith in order to direct energies along appropriate paths. The principle is to use a formulary such as: "I believe all Energy is One, but for such and such a purpose the Divine Aspect of So and So operates through this type of Archangel, that sort of Angel, and this particular kind of Spirit." Then an attitude of faith is adpoted towards these beings as intermediaries of Divine Energy on their respective levels of Consciousness, and an individual Adaptation made to them by means of whatever prayer or practice the Initiate may be capable of. Blind belief is not encouraged in the Mysteries of Light except in the Origin of Light, Life, and Love from whence all Energy emanates.
No intelligent Initiate believes that Angels or Spirits of any species are winged people in nightgowns flitting around Inner Space. However their Telesmic Images are shaped as Symbols, they themselves are Active Agencies of Awareness, or catigorical concentrations of Divine Consciousness, each existing for some particular purpose in the Plan of Perfection.
Another Excerpt from the highly recommended 'William G Gray - Inner Traditions of Magic'