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.

c. 1300, cristente, "Christians as a whole; state of being a Christian; the religion founded by Jesus," from Old French crestienté "Christendom; spiritual authority; baptism" (Modern French chrétienté), from Church Latin christianitatem (nominative christianitas), noun of state from christianus (see Christian). Gradually respelled to conform with Latin. Christendom is the older word for it. Old English also had cristennes.

constellation, added 1687 by Polish astronomer Johannes Hevelius, originally Scutum Sobiescanum "Shield of (King John) Sobeski," the 17c. Polish monarch famous as the savior of Christendom for his victory over the Ottomans at the Battle of Vienna (1683). The name was later shortened. From Latin scutum "shield" (see escutcheon). Middle English had scutifer "shield-bearer (late 14c.), from Medieval Latin.

Old English creda "article or statement of Christian belief, confession of faith," from Latin credo "I believe" (see credo). Broadening 17c. to mean "a statement of belief on any subject." Meaning "what is believed, accepted doctrine" is from 1610s. Related: Creedal.

A Creed, or Rule of Faith, or Symbol, is a confession of faith for public use, or a form of words setting forth with authority certain articles of belief, which are regarded by the framers as necessary for salvation, or at least for the well-being of the Christian Church. [Philip Schaff, "The Creeds of Christendom," 1877]

late 14c., "western part" (of the heavens or the earth), from Old French occident (12c.) or directly from Latin occidentem (nominative occidens) "western sky, sunset, part of the sky in which the sun sets," noun use of adjective meaning "setting," from present participle of occidere "fall down, go down" (see occasion (n.)). As a geopolitical term, sometimes with a capital O, always somewhat imprecise.

With the definite article, the west; western countries; specifically, those countries lying to the west of Asia and of that part of eastern Europe now or formerly constituting in general European Turkey; Christendom. Various countries, as Russia, may be classed either in the Occident or in the Orient. [Century Dictionary, 1895]