One of Zarathushtra's "most revolutionary concepts [is] that of the savior, the 'bringer of benefit' or the benefactor known in the Gathas as the Saoshyant. It is this savior figure - also referred to in the plural - who will bring about the renovation of the world."
"The seeds of later Zoroastrian eschatology are contained within Zarathushtra's introduction of the saoshyant. It is evident, though, that Zarathushtra was either anticipating the apocalyptic event in the near future or at least that he was hoping for it. Moreover, this concept of savior (which was later to have such a dramatic effect on the development of the post-exilic Jewish theological thought) is one of the chief means by which Zarathushtra attempts to break from the rigidity of the proto-Indo-Iranian tradition. In a sense he establishes, alongside an 'official' sacerdotal class, a preaching vocation of all believers (Ashavans), who would work with him towards the final event."

P. Clark, Zoroastrianism, Introduction to an Ancient Faith
(Peter Clark, Zoroastrianism, Introduction to an Ancient Faith, p. 15)

"The ages of the world. One fascinating mystical theme in the New Testament is that time consists of a series of ages. Each age of the world (or kingdom) is dominated by a powerful force or figure. This motif exists throughout the globe with a range of specific cultural meanings. In the 8^th century BC in Greece, the poet Hesiod described the ages of the world as four in number and symbolized by gold, silver, bronze, and iron, each age successively declining in morality. In India the four yugas (Sanskrit: "world ages"), symbolized by the four throws of a dice game, are also viewed as descending — though in repetitive cycles — from perfection to moral chaos. Other original schematizations of this theme can be found in the mythologies of Chinese, Polynesian, and American Indian cultures.

By the time the New Testament was written, Jewish apocalyptic writings (symbolic or cryptographic literature portraying God’s dramatic intervention in history and catastrophic dramas at the end of a cosmic epoch) had already produced theories of history that reworked Indo-Iranian notions about the ages of the world. Iranian concepts most influenced Christian views of time, history, and ultimate human destiny. The prophet Zoroaster (c. 7^th century BC) and his followers in Iran taught a doctrine of the four ages of the world in which each age was a different phase of struggle between two kinds of powers — light and darkness, goodness and evil, spirit and matter, infinity and finitude, health and sickness, time and eternity. The forces of good and evil battled for the allegiance and the souls of human beings. In the last days a promised savior (Saoshyant) would pronounce final judgement and announce the coming of a new world without end in which truth, immortality, and righteousness would have everlasting reign."

Encyclopedia Britannica (1992)

"During the 7th and 6th centuries BC the ancient polytheistic religion of the Iranians was reformed and given new dimensions by the prophet Zoroaster (or Zarathusthra.) Zoroaster's life dates have been traditionally given as c.628-551 BC, but many scholars argue for earlier dates. Linguistic evidence suggests that he was born in northeastern Iran, but the prophet's message was to spread throughout the Persian Empire. Adopted as the faith of the Persian kings, Zoroastrianism became the official religion of the Achaemenid empire and flourished under its successors, the Parthian and Sassanian empires. Its theology and cosmology may have influenced the development of Greek, later Jewish, Christian, and Muslim thought. The Muslim conquest of the 7th century AD marked the beginning of a steady decline of Zoroastrianism. Persecution resulted in the migration (about the 10th century) of the majority of Zoroastrians to India, where the Parsis of Bombay are their modern descendants.

The religion of ancient Iran was derived from that of the ancient Indo-Europeans, or Aryans. The language of the earliest Zoroastrian writings is close to that of the Indian Vedas, and much of the mythology is recognizably the same. . . .

The final period of 3,000 years was ushered in by the birth of Zoroaster, who revealed this struggle to humanity; the prophet is to be followed by three saviors, appearing at intervals of 1,000 years. At the appearance of the last, a day of judgment will occur, the drink of immortality will be offered to those who have fought against Ahriman, and a new creation will be established."

1998 Grolier (Grolier Interactive Inc.)

"He shall be the victorious Benefactor (Saoshyant) by name and World-renovator [Astavat-ereta] by name. He is Benefactor because he will benefit the entire physical world; he is World-renovator because he will establish the physical living existence indestructible. He will oppose the evil of the progeny of the biped and withstand the enmity produced by the faithful."

Avesta, Farvardin Yast 13.129
(World Scripture, IRF, Paragon House Publishing, 1995, p. 785.)

"Should we in a future world be permitted to hold high converse with the great departed, it may chance that in the Bactrian sage, who lived and taught almost before the dawn of history, we may find the spiritual patriarch, to whose lessons we have owed such a portion of our intellectual inheritance that we might hardly conceive what human belief would be now had Zarathushtra never existed."

Frances Power Cobbe
 Studies, New and Old, of Ethical and Social Subjects

"Thus from the moment the Jews first made contact with the Iranians they took over the typical Zoroastrian doctrine of an individual afterlife in which rewards are to be enjoyed and punishments endured. This Zoroastrian hope gained ever surer ground during the inter-testamentary period, and by the time of Christ it was upheld by the Pharisees, whose very name some scholars have interpreted as meaning `Persian', that is, the sect most open to Persian influence."

R.C. Zaehner, The Dawn & Twilight of Zoroastrianism
(R.C. Zaehner, The Dawn & Twilight of Zoroastrianism, p. 58.)

"One is tempted to say that all that was vital in Zarathushtra's message passed into Christianity through the Jewish exiles. . . It is impossible to revive a religion once the well-springs of the original revelation have been allowed to dry up, and once the sacred language itself has become so sacred that it is no longer understood even by those who set themselves up as its official interpreters."

R.C. Zaehner, The Dawn & Twilight of Zoroastrianism
(R.C. Zaehner, The Dawn & Twilight of Zoroastrianism, p. 171.)

"Without Zarathushtra there would be no Christ. He was the bridge, and the Romans burnt it."

Paul William Roberts, In Search of the birth of Jesus:
The Real Journey of the Magi

"How did the idea of two opposing forces (Satan & God) originate? It too is the result of conditions during the Hellenistic age, a period when ideas were exchanged widely among various religions and nations. The principle of dualism came from Zoroastrianism, .... This idea spread through the wide open Hellenistic world; the controversy between God and Satan is its reflection in Judaism. . . . 

The people have a heavenly representative, a guardian angel. This is a new concept of Zoroastrian origin. Previously the term `Malakh', angel, simply meant messenger of God."

Leo Trepp, A History of the Jewish Experience
(Leo Trepp, A History of the Jewish Experience, p. 54.)

"It is thought by many that this doctrine `Zoroastrianism' was a source of influence for both Eastern and Western beliefs - Hinduism and Buddhism in the East, and Judaism and Christianity in the West."

John R. Hinnells, Persian Mythology