Literally just the old 'law contrasted with chaos' shtick.
Faith, and by extension God, and by extension Law and Organization and Domination, is represented by and often takes the form of a swarm of flies.
God is the Saturn Devouring His Child, God is the He-figure without being a patriarch or progenitor of other deities or even male-gendered, God is the penultimate dictator who craves for everything to be under his control, God is the uniform swarm operating with a collective will and singular purpose, God wants to be everything so as to keep everything in order.
Faith is the atomized culture where the individual is illuminated like nuclear light, contributing to a glow alongside but separate but grouped to infinite other individuals.
People who have faith can do some of the following things:
A prayer to consume spirits with nuclear flame.
An invocation to call swarming, biting flies.
A chant to disorient everyone under the sun.
A chant to still movement and halt heat.
A hymn to imitate another living person.
Doubt, and by extension Lucifer, and by extension Awareness and Indecision and Agony, is represented by and often takes the form of a colorless white head with a hole where a face should be.
Lucifer is the fever-dream of morals and ethics, Lucifer is the Neuter-figure at a distance and never fully believed, Lucifer is the gentle Superego that craves nothing but well-reasoned balance, Lucifer is the monolith with a hundred thousand sides to explore and get lost inside, Lucifer wants everything so as to know what things are and what things aren't.
Doubt is the collective self-aware infinite that mutually supports itself because there is nothing but itself because all things are it.
People who doubt can do some of the following things:
A dance to drive spirits into frenzy.
A compact to link distant locations together.
A song to dissolve memories into liquid.
A rite to inflict endless terror on a person.
A ritual to hide oneself from any detection.
Disbelief politely and surely says fuck all to the above options.