Wordorigins.org

Church key, an American slang term for a bottle opener, is first attested to in 1951, although it is undoubtedly older.

It’s so called because the bottle openers resemble the heavy, ornate keys that unlock big, old doors like those found in churches. The origin may also be related to the irony of associating churches with drinking.¹

¹Historical Dictionary of American Slang, v. 1, A-G, edited by Jonathan Lighter (New York: Random House, 1994), 422.

The English name for the Asian country is not originally a native Chinese one. It first appears in Sanskrit writings about two thousand years ago. It was brought to Europe by Portuguese traders in the 16th century. The first English usage appears in 1555 in Richard Eden’s The Decades of the Newe Worlde or West India:

The great China whose kyng is thought...the greatest prince in the world.

The ultimate origin is not quite certain. Most commonly it is thought to come from the Ch’in (or Qin in the Pinyin transliteration system) dynasty of the 3rd century B.C. Alternatively, it could come from Jinan, an ancient city in Shandong province.

The porcelain product is so named because that technique of earthenware manufacture originated in China. It was brought to Europe in the 16th century by the Portuguese. Its appearance in English dates to at least 1634, when it was used by Thomas Herbert in his A Relation of Some Yeares Travaile:

They sell Callicoes, Cheney Sattin, Cheney ware.

China-ware was clipped to China within a few decades. From Henry Cogan’s The Voyages and Adventures of F.M. Pinto (1653):

A Present of certain very rich Pieces of China.

(Sources: Oxford English Dictionary, 2nd Edition; Place Names of the World, by Adrian Room)