Dear Mr. Yazdi Sidhwa,
I am fully aware that the modern Zartosthian Moobadan/theologians often reject that Deen e Zartoshti is Dualistic and they interpret Gahaan/Gaathaas in monotheistic way.
But do traditional Zartoshtians really believe in a cosmic dualism, Ourmazd and Ahriman as two direct competitors?!
(Modern Moobadaan say Angra-Manyu and Sepanta-Manyu are two adversaries and Ahuramazda has not any rival but it seems the traditional Zoroastrians believed in a 'Ahuramazda vs Ahriman' theory, such as the informations of Bundahishn)