I would say that Mazdayasna is an existentialist religion. Whatever we think, whatever we say, whatever we do, become a part of ourselves, of our historical existence, of our identity. This is what inspired Nietzsche to use the Zarathushtra character in his work. Nietzsche referred to Zarathushtra as "the original ethicist" in his book "Ecce Homo".
So a good thought leading to a good word leading to a good act turn us into a positive existence. Bad thoughts, words, deeds of course have the opposite effect. There is no need for punishment within such a system. We are rewarding and punishing ourselves through the very acts we commit. Actually, all the Indo-European religions look at actions in this ethical rather than moral way. Please compare with the Hinduist concept of karma if you like.
2007/9/5, Jehan Bagli <email@example.com>:
Dear Friends:So how is sin atoned for in Zarathustra's system of Sacrifice?The term sacrifice is often loosely used in religious dialogues. It is used by some, for the offerings and veneration in Zarathushtrian system.However in the belief system of Asho Zarathusht there is no involvement of Punishment or atonement for an act of deceit or evil deed. A sin is a violation of moral law. In zarathushtrian theology any choice that deviates from the law of Asha, the law of what is good and right for a situation, isbad and deceitful. The way to set this right is for the person to think through a clear and peaceful mind ( Vohu Manah) and seek for the path of honest and righteous way to handle each situation.
The very responsibility of returning to the quest for Truth lies with the individual and not with any power of the Divine. The way to bring evil to the path of Good is through Good thinking. To learn and evolve (both physically and spiritually) from the mistakes that one makes. For the divine is within each human being and each one of us has the responsibility to act in a way that we can bring the Good Rule ( Khshthra vairya) in close proximity to our Corporeal world. A world, that has been flawed and tinted by the evil and undesirable choices. Thereby not only do mankind tend to be one with God individually, but also help others recognize divine within and make the whole world a better place to live in.With peace and Guidance from Mazda