Meaning of names of religions

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Catholic
c.1350, "of the doctrines of the ancient Church," lit. "universally accepted," from L.L. catholicus "universal, general," from Gk. katholikos, from phrase kath' holou, from kata "about" + gen. of holos "whole." Applied to the Church in Rome c.1554, after the Reformation.

Protestant
1539, from Ger. or Fr. protestant, from L. protestantem (nom. protestans), prp. of protestari (see protest). Originally used of Ger. princes and free cities who declared their dissent from the decision of the Diet of Speyer (1529) denouncing the Reformation. The word was taken up by the Lutherans in Germany (Swiss and French preferred Reformed). It became the general word for "adherents of the Reformation in Germany," then "member of any Western church outside the Roman communion;" a sense first attested in Eng. in 1553.

"In the 17c., 'protestant' was primarily opposed to 'papist,' and thus accepted by English Churchmen generally; in more recent times, being generally opposed to 'Roman Catholic,' or ... to 'Catholic,' ... it is viewed with disfavour by those who lay stress on the claim of the Anglican Church to be equally Catholic with the Roman." [OED]​

Often contemptuous shortened form Prot is from 1725, in Irish English. Protestant (work) ethic (1926) is taken from Max Weber's work "Die protestantische Ethik und der 'Geist' des Kapitalismus" (1904).

Pagan
c.1375, from L.L. paganus "pagan," in classical L. "villager, rustic, civilian," from pagus "rural district," originally "district limited by markers," thus related to pangere "to fix, fasten," from PIE base *pag- "to fix" (see pact). Religious sense is often said to derive from conservative rural adherence to the old gods after the Christianization of Roman towns and cities; but the word in this sense predates that period in Church history, and it is more likely derived from the use of paganus in Roman military jargon for "civilian, incompetent soldier," which Christians (Tertullian, c.202; Augustine) picked up with the military imagery of the early Church (e.g. milites "soldier of Christ," etc.). Applied to modern pantheists and nature-worshippers from 1908. Paganism is attested from 1433.

Judaism
1494 (attested in Anglo-L. from 1251), from L.L. Judaismus (Tertullian), from Gk. Ioudaismos, from Ioudaios "Jew" (see Jew). The Anglo-L. reference is to a special tax levied on the Jews of England.
Jew
c.1175 (in plural, giwis), from Anglo-Fr. iuw, from O.Fr. giu, from L. JudaeumJudaeus), from Gk. Ioudaios, from Aramaic jehudhai (Heb. y'hudiY'hudah "Judah," lit. "celebrated," name of Jacob's fourth son and of the tribe descended from him. Replaced O.E. Iudeas "the Jews." Originally, "Hebrew of the kingdom of Judah." Jews' harp "simple mouth harp" is from 1584, earlier Jews' trump (1545); the connection with Jewishness is obscure. Jew-baiting first recorded 1853, in ref. to Ger. Judenhetze. In uneducated times, inexplicable ancient artifacts were credited to Jews, based on the biblical chronology of history: e.g. Jews' money (1577) "Roman coins found in England." In Greece, after Christianity had erased the memory of classical glory, ruins of pagan temples were called "Jews' castles."

Buddha
1681, from Pali, lit. "awakened, enlightened," pp. of budh "to awake, know, perceive," related to Skt. bodhati "is awake, observes, understands." Title given by his adherents to the man who taught this path, Siddhartha Gautama, also known to them as Sakyamuni "Sage of the Sakyas" (his family clan), who lived in northern India 5c. B.C.E. Buddhist, Buddhism first recorded 1801.

Islam
"religious system revealed by Muhammad," 1818, from Ar., lit. "submission" (to the will of God), from root of aslama "he resigned, he surrendered, he submitted," causative conjunction of salima "he was safe," and related to salam "peace." Islamic is attested from 1791. Earlier Eng. names for the faith include Muhammadism (1614) and Ismaelism (1604), which in part is from Ishmaelite, a name formerly given (esp. by Jews) to Arabs, as descendants of Ishmael (q.v.), and in part from Ar. Ismailiy, name of the Shiite sect that after 765 C.E. followed the Imamship through descendants of Ismail (Ar. for Ishmael), eldest son of Jafar, the sixth Imam. The Ismailians were not numerous, but among them were the powerful Fatimid dynasty in Egypt and the Assassins, both of whom loomed large in European imagination.

Hindu
1662, from Pers. Hindu (adj. & noun) "Indian," from Hind "India," from Skt. sindhu "river," specifically the Indus; hence "region of the Indus," gradually extended across northern India. Hinduism, blanket term for "polytheism of India," is from 1829.

Sikh
1781, sect established 16c. in Punjab by Nanak Shah, from Hindi sikh "disciple," from Skt. siksati "studies, learns," related to saknoti "he is able, he is strong."

Taoïsm
religious system founded by Lao Tzu (b. 604 B.C.E.), 1839, from Chinese tao "way, path, right way (of life), reason." Tao itself was used in Eng. from 1736.

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