Who was the first to preach about two opposing religious forces in the world?

The concept of two opposing religious forces in the world can be traced back to Zoroastrianism, an ancient Iranian religion founded by the prophet Zoroaster (or Zarathustra). Zoroaster preached about the dualistic nature of the universe, with the forces of good (Ahura Mazda) and evil (Angra Mainyu) in constant conflict.