Encountering them is unavoidable if you seek to talk or see guides/angels or leave the physical body.

Better to know and believe they can't posses you than to fear being possessed. Fear is their power. They will only stay around if you think they have power over you or you fear them. Otherwise once their presence has no effect over you they will quickly leave. As you will no longer be a source of food.

Whether you have faith in source, god or yourself doesn't matter as long as you don't have faith in dark entities.
Fear and faith are the same just opposites and both equally powerful choose which one to empower in yourself.