Also, to be very fair I do worship and take as authoritative the Old and New Testaments because the Logos inspired them; and I also highly esteem the Vedas, Upanishads, Bhasyas, Itihas etc. both because they reflect the divine image in man by the priceless wisdom they contain and also because my fathers wrote them.Dear Gustav,
You do follow an Abrahamic faith yourself and you mentioned your brother is a Muslim...your bro would be knowing that Surah Al Baqarah is the biggest chapter in the Quran.
So all these are equally important to you along with the Upanishad cos your gotra is still valid and you on your own are trying to keep your vedic heritage alive by trying to help your uncle to continue the lineage.
Your vedic heritage still speaks so much through you.
In fact its through you bringing up the Upanishad shloka we got to know about the ayurvedic herb uksha and vrshaba and analysed the shloka to some extent.
At the same time we should not underestimate any tribe be it from India or from the Middle East.
We can learn from anything..anywhere...everything ..everywhere..all at once.
The Koran and Hadiths on the other hand (in my humble opinion) contain zero wisdom and are instead a hodgepodge of ramblings by a confused gang of adulterous robbers and marauders (and their successors), having nothing to do with either the divine image or my ancestors.
So I by no means put it on the same level as either the Bible or the Vedas. Far from it.