the root of western religion does not set up duality. Duality comes from Zoroaster and Iran. Talmudic thought does not work in binary. Duality is the root of science which comes from Cartesian thought and the idea of separation between mind and body.
Judea-Monotheism does not have an avatar of evil. Satan has some "folk stories", but his appearance in the old testament isn't clarified. the idea in Jewish thought is to get closer to g-d. Proximity is a relative concept. read the Talmud and check.
many argue that Christianity was a bastardization of Zoraoster, Hellenism and Judaism. angel wars and the concept of wars between dark angels and angels of light are ideas that developed out of Persia.
In fact there have been archeological finds of "Holy Scrolls" from the period of Persian influence on Judaic thought and they are full of all kinds of strange "Angel" wars. If you look at Zoroaster art you will see the parallel between their religion and what developed afterwards. The lost scrolls are not cannon today in either Judaism or Christianity, but you can clearly see the philosophical evolution after Zoroaster's influence. I'm not a person who believes in the stiffness in scripture, mostly because I have seen the evolution in thought. for me to see spirituality as binary is as pagan as worshipping something material like an idol. to believe a document is pure is to say it is a g-d itself and to do this is pagan. I am not literal with scripture and no learned Jew would be because to do so would be to glorify something that is material.
also the duality in buddhism is really not a duality at all. I don't claim to be of that philosophy, but that duality is symbiotic and dependent in each other. for me that is a bit systematic. eastern duality is really a more one like metaphor. too complicated for me. I don't apply math on my g-d.