Etymology
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caliph (n.)
late 14c., "ruler of a Muslim country," from Old French caliphe (12c., also algalife), from Medieval Latin califa, from Arabic khalifa "successor" (from khalafa "succeed"). Title given to the successor of Muhammad as leader of the community and defender of the faith; originally Abu-Bakr, who succeeded Muhammad in the role of leader of the faithful after the prophet's death.
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edify (v.)
Origin and meaning of edify
mid-14c., "to build, construct," also, in figurative use, "to build up morally or in faith," from Old French edefiier (12c., Modern French édifier) "build; install; teach, instruct (morally)," from Latin aedificare "to build, construct," in Late Latin "improve spiritually, instruct" (see edifice). Related: Edified; edifying.
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fidelity (n.)

early 15c., "faithfulness, devotion," from Old French fidélité (15c.), from Latin fidelitatem (nominative fidelitas) "faithfulness, adherence, trustiness," from fidelis "faithful, true, trusty, sincere," from fides "faith" (from PIE root *bheidh- "to trust, confide, persuade"). From 1530s as "faithful adherence to truth or reality;" specifically of sound reproduction from 1878.

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credulity (n.)

early 15c., "faith, belief," from Old French credulité (12c.), from Latin credulitatem (nominative credulitas) "easiness of belief, rash confidence," noun of quality from credulus "that easily believes, trustful," from credere "to believe" (see credo). Meaning "a weak or ignorant disregard of the importance of evidence, a disposition too ready to believe," especially absurd or impossible things, is from 1540s.

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infidelity (n.)
c. 1400, "want of faith, unbelief in religion; false belief, paganism;" also (early 15c.) "unfaithfulness or disloyalty to a person" (originally to a sovereign, by 16c. to a lover or spouse), from French infidélité (12c.) or directly from Latin infidelitatem (nominative infidelitas) "unfaithfulness, faithlessness," noun of quality from infidelis "unfaithful, unbelieving" (see infidel).
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immobile (adj.)
mid-14c., originally of property; by c. 1400 "steadfast, unmovable" (of faith, etc.), from Old French immoble "immovable, fixed, motionless" (13c., Modern French immeuble), from Latin immobilis "immovable" (also, figuratively, "hard-hearted"), from assimilated form of in- "not, opposite of" (see in- (1)) + mobilis (see mobile (adj.)). Related: Immobilism "policy of extreme conservatism" (1853).
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Christendom (n.)

Old English cristendom "Christianity, state of being a Christian, profession of faith in Christ by baptism," from cristen (see Christian) + -dom, suffix of condition or quality. The native formation, crowded out by Latinate Christianity except in the sense of "lands where Christianity is the dominant religion" (late 14c.). Similar formations are found in Scandinavian languages.

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lapse (v.)
early 15c., to go by, pass (of time), from lapse (n.) and from Latin lapsare "to lose one's footing, slip, slide," from stem of labi "to slip, glide, fall." Meaning "fail in duty or faith" is from 1630s. Meaning "become void, revert due to some failure or non-action by the holder" is from 1726. Related: Lapsed; lapses; lapsing.
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devil's advocate (n.)

"one who advocates the contrary side," 1760, translating Latin advocatus diaboli, in the Catholic Church, a promoter of the faith and officer of the Sacred Congregation of Rites whose job it is to urge against the canonization of a candidate for sainthood. "[F]ar from being the whitewasher of the wicked, the [devil's advocate] is the blackener of the good." [Fowler]. Said to have been first employed in connection with the beatification of St. Lorenzo Giustiniani under Leo X (1513-21).

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Baha'i (n.)
1889, Beha'i, mystical, tolerant Iranian religion founded by a Mirza Ali Mohammed ibn Radhik, Shiraz merchant executed for heresy in 1850, and named for his leading disciple, Baha Allah (Persian "splendor of God;" ultimately from Arabic). It also is sometimes called Babism, after the name taken by the founder, Bab-ed-Din, "gate of the faith."
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