argumentum ad fidem

[ärgyo͞omĕnʹtəm ăd fĭʹdĕm, IPA: /ɑːɡjuːˈmɛntəm æd ˈfɪdɛm/]
argumentum ad fidem (plural argumenta ad fidem)
(rhetoric) A fallacious argument that asserts the truth of a proposition by an appeal to pious testimony or religious revelation.