Complex sentence: Priests and other enlightened people can instruct the less enlightened on the message of the deity, the sacred, or semi-sacred, declare themselves to be the medium between the commons and the more holy unobservable beings.
Split into simpler sentences: Priests and other enlightened people can instruct the less enlightened on the message of the deity. The sacred, or semi-sacred, declare themselves to be the medium between the commons and the more holy unobservable beings.