Zoroastrian teaching portrays reality as shaped by two fundamentally opposed orientations, one toward good and one toward evil, both ethical and cosmic in scope. Good is aligned with Ahura Mazda, the Wise Lord, and with Spenta Mainyu, the Bounteous or Holy Spirit. It is expressed through asha—truth, right order, righteousness, and light—and manifests in good thoughts, good words, and good deeds. This side of existence is associated with creation, life, beneficence, justice, and divine wisdom, and it includes right worship and care for the created world: water, fire, earth, plants, and animals. In this vision, good is not merely moral correctness but participation in the very structure and destiny of reality as intended by Ahura Mazda.

Evil, by contrast, is associated with Angra Mainyu or Ahriman, the Destructive Spirit, who stands in radical opposition to Ahura Mazda’s order. Evil is defined through druj—the Lie—embodying falsehood, deceit, wickedness, chaos, and darkness. It shows itself in bad thoughts, bad words, and bad deeds, and is linked with violence, cruelty, oppression, destruction, death, and ignorance. It also includes the pollution and corruption of the natural elements and the distortion of proper worship through idolatry, demon‑worship, and destructive magic. Rather than being a creative power in its own right, evil is portrayed as parasitic, corrupting and distorting what has been created good.

Human beings stand at the crossroads of these two orientations and are endowed with genuine moral responsibility. Each person is called to choose, moment by moment, between asha and druj, thereby aligning either with Ahura Mazda and the forces of good or with Angra Mainyu and the forces of evil. This choice is not merely private; it is participation in a vast cosmic struggle that encompasses both the visible and invisible dimensions of existence. Individual destiny after death, including judgment at the Chinvat Bridge and the prospect of paradise or punishment, is understood in light of these choices. At the same time, every act of good thought, word, and deed is seen as contributing to the ultimate victory of good and the final restoration of the world, when the divine order will stand unobstructed and evil will be definitively overcome.