 Complete the following phrase:  Religion in Iran has been shaped by multiple religions and sects over the course of the countrys history. Zoroastrianism was the main religion during the Achaemenid Empire 550330 BC, the Parthian Empire 247 BC  224 AD and the Sasanian Empire 224651 AD. In 651 AD, the Rashidun Caliphate conquered Persia and spread Islam as the main religion. Sunnism was the predomit form of Islam before the devastating 