In Exodus 3:14, God revealed Himself as “I AM that I AM” (יהוה). Sometime before the 1st century A.D., it became common for Judaites to superstitiously avoid saying the divine name for fear of misusing it and breaking the commandment, “You shall not take the name of Yahweh your God in vain” (Ex. 20:15; Deut. 5:11 — 3rd for Judaites and Protestants, 2nd for Catholics and Lutherans). Whenever they read Scripture aloud and encountered the divine name, they substituted another Hebrew word, “Adonai” (which means “Lord” or “my Lord”), in its place.
When Hebrew eventually developed written vowels, which appeared as small marks called vowel points and were placed above and below the consonants of a word, some Judaites in the 6th or 7th century began to place the vowel points for “Adonai” over the consonants for “Yahweh” to remind the reader of Scripture to say “Adonai” whenever he read “Yahweh.”
Around the 13th century, when Christian scholars took the consonants of “YHWH” and pronounced it with the vowels of “Adonai,” it resulted in the sound, “Yahowah.” This was then Latinized as “Jehovah,” the first recorded use of this spelling made by Raymundus Martini, a Spanish Dominican monk, in 1270.
Without argument, the precise vowels and pronunciation are unknown. While most English translations opt to use “LORD” in place of the Tetragrammaton, YHWH, the ASV (American Standard Version, 1901) and LSB (Legacy Standard Bible, 2021) are unique. The ASV opted to render it as “Jehovah,” while the LSB opted to render it as “Yahweh.” After all, it is God’s name we are talking about here, which certainly is not Allah.
The practice of rendering it “LORD,” as opposed to “Lord” (which typically renders the Hebrew, “Adonai”), follows the custom intitated by the Septuagint (which used the Greek, “Kurios”), and perpetuated in the Latin Vulgate. Some Judaite traditions, however, choose to render YHWH as “HaShem” (literally, “the Name”).
Proper names are never translated but rather transliterated. The letter J was the last letter added to the English alphabet. The Latinized Jesus (or Iesus, as it originally appeared) comes from the Greek, Iésous (transliteration of Ἰησοῦς), and the Hebrew, Yehoshua (transliteration of יְהוֹשׁוּעַ), which both mean “Yahweh saves” or “Yahweh is salvation.”
Since certain letters in certain languages have a different sound than in English, such as the letter J in Spanish having both an H sound (as in “jalepeño”) and a Y sound (as in “Jaci”), could it be possible that the Y and I words in Hebrew and Greek were pronounced with a sound similar to the sound of J in English? Well, according to www.howtopronounce.com, Ἰησοῦς is pronounced with an H sound (the same as the Spanish pronunciation of Jesus), and יְהוֹשׁוּעַ is pronounced with a Y sound. So where and why did words like Joshua and Jesus, which start with Y and I in the Hebrew and Greek (respectively), suddenly get the sound of J (such as George)?