In 194 Watchtower Bible And Tract Society of New York, INC (I have it stated this way in their booklet in my native language translation of 1987) stated that the Jews came up with the word Jehovah in second half of the first millennium.
As far as I know, the word doesn't appear in the ancient scripts.
God is not a man and doesn't need to be known by a man made name-tag. Man should know God from His word and acts.
The word "onoma" used to mean authority among other things. Thus God changed "names" of some people.
The followers of Christ are granted intimacy to call God "our Father".
Alas, not many seem to follow the Lord Jesus Christ.
It is pretty hard to trust anything the Watchtowers says. I have most of their "books" .... and especially the early ones from the 1800's up to the 1920's.
They had so many falsehoods and failed prophecies in them , the watchtower gathered them back up so as not to be embarrassed (caught) (exposed).
Some of the books did get distributed
after the offending pages were cut out .... .... but I have the
very rare originals with all the pages still intact.
It makes Watchtower furious , they even offered me $300 for one small book so they could destroy it. I told them no.
Watchtower has made so many blatant errors and mistakes I am surprised they are still around. Cult expert Walter Martin says they survive because the congregants are the type of folks who cannot always think for themselves and are easily mislead.
It is sad to see nice people get led astray by clever liars from the Watchtower headquarters..
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Back to the name of God issues ...... The most widely accepted pronunciation of the Tetragrammaton (YHWH) is YAHWEH , though JEHOVAH is used in many Bibles,
YHWH has been used since Genesis in the bible .... and the Mesha Stele is a stone (clay) inscription from about 840 BC so it is not something invented by the Jews in the first millennium.
Proper pronunciation of YHWH is unknown because Jews were prohibited from saying it.
So Yes ... the vowels are added by man and may not be completely accurate.
But at this moment we can be certain that the Watchtower information is not reliable.
Nevertheless , we know for certain YHWH means "I AM WHO I AM" when God spoke to Moses.
י. YHWH in Hebrew looks something like this
יְהֹוָה