Merriam-Webster describes Artemis as "a Greek moon goddess often portrayed as a virgin huntress — compare DIANA". The Online Etymological Dictionary says of Diana: "ancient Italian goddess of the moon, patroness of virginity and hunting, later identified with Greek Artemis, and through her with eastern goddesses such as Diana of Ephesus." To summarize, both Artemis and Diana are the moon goddess of hunting. The two are the same goddess - Diana being the Latin name of Artemis. Since English developed partly from Latin, English took "Diana" to refer to this goddess. It is quite telling that in English-speaking countries many women are named "Diana" but hardly anybody is named "Artemis". The KJV, being an English translation, used the English name to translate the name of the goddess. If the true God, who is called “θεός” in Greek, can be translated into English as “God” and not transliterated as “Theos”, then surely it is fine to translate “Artemis” as “Diana” rather than transliterating the word.
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