Synonyms for Demonism:

n.

•cognition (noun)
satanism, diabolism.
•sectarianism (noun)
demonolatry, heterodoxy, sectarianism, heathenism, barbarism, fetishism, factionalism, dissidence, paganism, nonconformity, iconolatry, Denominationalist, heresy, pantheistic, idolatry, non-orthodoxy, non-belief, atheism, bohemian, non-religiousness.
•sorcery (noun)
clairvoyance, sorcery, diabolism, astrology, witchcraft, Occultism, wizardry, palmistry, horoscopy, satanism, fortune telling, necromancing, Divining, augury, magic, devilry.

Other synonyms:

•n.
sorcery.