Disclaimer: I do not use the book Avesta or follow the Zoroastrian religion so do feel free to clarify anything you feel needs clarifying.
Before Abraham was spoken to by Melchizedek (Archangel Michael) or the Creator his religion was fire worship. Abraham was worshipping the deity of Zoroastrianism Ahura Mazda until he was met. This is stated in Genesis chapter 14 verse 18-19, where it reads:
And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God. And he blessed him, and said, Blessed be Abram of the most high God, possessor of heaven and earth.
Abraham was a Chaldean of Ur and Ur means fire. So it seems that the Chaldean of Ur were a fire worshipping people, worshipping fire as a manifestation of God. Abraham was was known as Abram at the time and was later converted to Abraham. He was told to leave Chaldea when he was met.
Zoroastrianism is simply fire worship and its participants are called fire worshippers (Zorasters). This form of worship was attributed to Zarathustra who was taught by Ahura Mazda and wrote the prayer book Avesta.
Zarathustra (In Greek Zoraster) founder of Zorastrianism
Nobody truly knows when he lived but the Greeks who call him Zoraster have many speculation. He is said to have lived at a time before the philosopher Plato was born.
Ahura Mazda is said to be a benevolent deity. The word or name Ahura means ‘spirit, lord’ and the name Mazda means ‘wise’. Putting the two words together gives ‘the wise lord or spirit’. Zarathustra said that Ahura Mazda came from the sun. He is depicted with wings and a sun disk.
The symbol of the sun disk with wings came from the Khemet (Egypt) which was a symbol of the sun. Zoroastrianism is based on what some say is a Persian mythology. It is still been practised today (21st Century).
Khemet(Egypt) sun disk with wings
In the book of Malachi in the Bible it says in chapter 4 verse 2:
…the Sun of righteousness arise with healing in his wings
This is referring to the sun disk with wings (don’t forget that the Old Testament takes place in Africa right unto the New Testament).
Ahura is also known as Ormuzd or Ohrmazd God of The Sun, son of Zurvan who is the god of infinite time, who was a hermaphrodite.
Zurvan fathered Ahriman (The Evil one).
Another image of Ahriman
Zarathustra and his followers migrated to India in the 10th Century and became known as the Parsis (meaning people from Pars or Persia). It seems that Islam has replaced Zoroastrian in Iran and other Persian countries.
Reminder: The Creator is Universal not confined to a book