[Lurking Libertarian]

According to the OT, the actual name of God, if you ever got it right, would get you killed, unless you were the High Priest of the Temple in Jerusalem. The actual name was not intended to be thrown about carelessly, because it contains too much power for most people.

The Hebrew Bible ("Old Testament" to Christians) does not actually say that, and in fact mentions people using the name YHVH (however it was actually pronounced) in common speech. (See, e.g., Ruth 2:4). In Second Temple times (ca. 500 BCE- 70 CE), the custom became not to pronounce that name in ordinary speech; at first, it was used only by priests at services in the Temple, and eventually (according to the Talmud) only by the High Priest at the service on Yom Kippur.