Zoroastrianism is a dualistic religion that was the official religion of Persia for 1000 years, from 600s BCE to 600s CE. It was founded about 3500 years ago in what is now Iran by a prophet named Zarathustra. According to Zarathustra (or Zoroaster), the creator God Ahura Mazda revealed the truth to him that forms the foundation of the religion:
There is a constant battle between Good and Evil and between the creator God Ahura Mazda and the God of destruction Angra Mainyu. The world was created perfect by Ahura Mazda, through His creative energy called Spenta Mainyu, but Angra Mainyu injects impurity into creation through disease, famine, war, age, etc.
Humans have free will and thus the ability to choose between the path of truth or asha or the path of deceit druj. Those who choose the path of truth are helpers of Ahura Mazda and those who choose the path of deceit help Angra Mainyu. If ever there is a time when more people choose truth, then paradise will reign on Earth.