The Rabbis of the Jewish tribe in Yatrib (400 AD) prophesied that according to Torah a messenger would come for the Arabs.
I said as much myself in the post - the Holy Spirit is found throughout the OT as well. Except I would disagree about anything being "before Jesus." John 1 denies that clearly. In scripture, the Spirit of Truth and the Holy Spirit are one and the same. Your narrative states at the end that the Spirit of Truth is in fact Mohammed, who has never been around before. The two concepts therefore cannot be reconciled.
The Rabbis of the Jewish tribe in Yatrib (400 AD) prophesied that according to Torah a messenger would come for the Arabs.
Please elaborate. Where in the Torah does it say that a messenger would come specifically for the Arabs? I do think it is pretty clear that the Torah (definitely the Tanakh) points to Jesus coming for all mankind.
You have not addressed the fact that Mohammed and Jesus were in no way similar in teachings or lifestyle.