Doesn't the language similarity between avesta and Vedas put "apaurausheyata" of Vedas to question? Many verses of vedas are repeated in avesta.
I got some interesting points from this website. Though I don't know whether they are authentic or not, I am simply summarizing it.
There are no ancient Zoroastrian texts that refer to their language as “Avestan” In fact no one knew of any original Zoroastrian language of any name, be it Avestan or any other name. Then why and how do present day historians and linguists say the Vedas and the Zend Avesta represent separate religions that split off from a common source?
In the late 1700s a man called Anquetil du Perron came to India and lived for a few months with Parsi priests in Surat, who taught him what they knew of Zoroastrian chants (gathas) and rituals. Perron also collected some Zoroastrian texts and returned to Europe where he wrote a book in French called “Zend Avesta – Ouvrage du Zoroaster” meaning “Zend Avesta – the work of Zoroaster.
Perron’s work was later validated and corrected by a man called Eugene Burnouf by using a 13th century Sanskrit book by an Indian called Neryosangh Dhaval. That book was a Sanskrit translation of a Pahlavi language version of Zoroastrian holy texts.
So whatever is written in history about the 3000 plus year old “Zend Avesta” is derived from verbal accounts of 17th century Parsi scholars, contemporary texts and a 13th century book that was written in Pahlavi language and translated to Sanskrit.
A 3000 year gap between the original language and the translation does not inspire confidence about the linguistic theories regarding the identity of the original Zoroastrian language.
- So, the article concludes its first part by saying both the Vedas and religious book of Zoroastrianism have a same source.