How did Zoroastrian purity rules affect daily religious life?

In Zoroastrianism, purity rules were central to daily religious life, reflecting a rigorous system of casuistry that categorized actions as either allowed or forbidden. This framework was deeply rooted in the dualistic struggle between the forces of light, represented by Ahura Mazdā, and the forces of darkness, Angra Mainyu.1

The impact on daily life included:

• Ritual Observance: Believers were expected to adhere to strict priestly injunctions regarding cleanliness. This included the careful custody of sacred fires, which were considered the highest manifestation of the divine on earth; priests often covered their mouths to prevent their breath from polluting the fire.1
• Avoidance of Pollution: Contact with death was considered a serious source of pollution. The religion strictly forbade polluting the earth with corpses, mandating that the dead be exposed to the elements instead.1
• System of Expiation: Because pollution was viewed as a serious offense to the divine, a detailed system of expiation was developed. Individuals who encountered pollution were required to undergo purification rites, such as the baresnum, which involved elaborate washing with water and consecrated cow’s urine (gomez).21
• Orthodoxy: The emphasis on purity fostered a culture of strict obedience to religious authority. Non-orthodox customs were often viewed as a pollution of the land, which justified the state-sanctioned suppression of heretical practices.1