From Longman Dictionary of Contemporary Englishan article of faithan article of faithsomething that you feel very strongly about so that it affects how you think or behave → article
Examples from the Corpus
an article of faith• One must accept it as an article of faith, sufficient unto itself, for all time.• When only seeing is believing the unseen reproductive anatomy of the female can not be an article of faith.• It would be an article of faith with him to believe that.• That is an article of faith for him.• But the idea is practically an article of faith among Republicans elected in the 1990s.• It was an article of faith to Be There, with or without the goods. 