Greetings:
Do you not know that "Jah" is the legitimate name of God. The name Jah is found throughout the Hebrew scriptures. Have you not tried reading a Hebrew interlinear to see this? Examples of the use of Jah are found even in many peoples' names such as: IsaIAH (meaning Salvation of Jah), JeremIAH (meaning Jah loosens), ZedekIAH (meaning Jah is Righteousness), ZephanIAH (meaning Jah has concealed), ZecharIAH (meaning Jah has Remembered), AbiJAH (meaning My God is Jah), etc., etc., etc. The list goes on and on.
The name of God as described in Exodus, which name we know as Yahweh or Jahveh simply means Jah Causes to Become. The name Jah can be found in many places in the Bible and is a legitimate name. Jah is the name. Anything added to it before or after just defines or describes Jah is all.
If you have the big Reference Bible of the New World Translation, check out page 1562, top of the page, and it will show all the references for this form of the Divine Name.
Jesus is not just any messiah of any household god, he is the MessIAH (the anointed not just of any god, but especially and specially the Anointed of Jah).
The witnesses (the Society) know this, but play it down. The name of Jah is not slang, is not derogatory.
--Inkie