Late 18th century: euphemism for God.

• God from Old English:

  The Old English word God is related to similar words in German and in Scandinavian languages, but not to the Latin and Greek words, which were deus (see divine) and theos (as in theology (Late Middle English)). The top gallery in a theatre is known as the gods—the original term in the 1750s was the regions of the gods, because the seats were high up and therefore close to the heavens. Godfather and godmother has been used since around ad 1000. Godfather meaning ‘a leader of the American Mafia’ has been a familiar term since Mario Puzo's novel The Godfather (1969) filmed in 1972, but was first recorded in the early 1960s. The origins of the British national anthem God save the Queen (or King) are not known for sure, but the song was definitely sung in London theatres in 1745, when the country was threatened by the Jacobite uprising led by the Young Pretender, Bonnie Prince Charlie, and the words and tune probably date from the previous century. ‘God save the king’ was a password in the navy as early as 1545—‘long to reign over us’ was the correct response. The exclamations gosh (mid 18th century) and golly (mid 18th century) were originally ways to avoid taking God's name in vain. See also lap