zoroastrianism

I am not religious but I was listening to an interview with a Zoroastrian priest and he described the religion as 'a path of reason' and 'it's guiding principles are about the importance of critical and rational thinking' and these core principles are about 'the importance of free will' and 'zoroaster was the first postoralist shaman that promoted individual freedom' and he further stated that 'he was the first human to describe a universe free from destiny' and 'the humans have absolute freedom'. I found that very interesting and I was familiar with the theory of dualism and the idea that evil is warranted by the polar opposite, and I can't help but feel that zoroastraism is an ancient shamanic philosophy that I'd like to learn more about. What do you know about Zoroastrianism?