From Webster’s Dictionary…here the definition of faith:

Main Entry: 1faith Pronunciation: ‘fAthFunction: nounInflected Form(s): plural faiths /’fAths, sometimes ‘fA[th]z/Etymology: Middle English feith, from Old French feid, foi, from Latin fides; akin to Latin fidere to trust — more at BIDE

1 a : allegiance to duty or a person : LOYALTY b (1) : fidelity to one’s promises (2) : sincerity of intentions

2 a (1) : belief and trust in and loyalty to God (2) : belief in the traditional doctrines of a religion b (1) : firm belief in something for which there is no proof (2) : complete trust

3 : something that is believed especially with strong conviction; especially : a system of religious beliefs

synonym see BELIEF–
in faith : without doubt or question : VERILY