Which Persian Religion Influenced Christianity, Islam, & Judaism?

Long before Jesus or the prophet Mohammed, there was another major religion in the Middle East. The ancient Persian Empire followed a faith known as Zoroastrianism, based on the teachings of an even more ancient prophet. This religion played a key role in the development of today's major world religions, interacting with Judaism and later Islam, and through Judaism coming to influence Christianity as well.

Zoroastrianism was founded in ancient Persia (modern-day Iran) by a man named Zarathustra, known to the ancient Greeks as Zoroaster. It is not known with certainty when he lived, though many scholars place his birth and death around 1000 B.C. He reformed Persia's older polytheistic faith to emphasize a basic duality between good and evil. A version of beliefs based on his teachings became the official religion of the Persian Achaemenid Empire, and continued to be a major religion in Persia until Islam arrived in the seventh century.

Zoroastrians believe in one supreme god of good who will eventually triumph over the god of evil, and that each side of this duality employs angels and demons, respectively, in the struggle for influence over humankind. Zoroaster considered humans to have free will and the responsibility to bring about the ultimate triumph of good; the religion's central motto is "good thoughts, good words, good deeds." This respect for free will means that modern Zoroastrians rarely pressure others to join their religion, and some even believe that Zoroastrianism should stay within its own ethnic group.

Judaism and Zoroastrianism, which both developed during the centuries prior to the birth of Christ, have many features in common. The Judeo-Christian concepts of heaven and hell, the Messiah and a future judgment day may have come from Zoroastrianism, and most scholars believe that the Jewish and Christian belief in angels and demons, as well as resurrection and eternal life, were influenced by the teachings of Zoroaster. The Zoroastrian belief in only two gods, and in the triumph of the good god, may also have influenced the Jewish, Christian and later Muslim conviction that there is only one real God.

After Muslim conquerors arrived in Persia in the seventh century, most Zoroastrians eventually converted to Islam, possibly because their leaders had been vanquished and the belief system of Islam seemed similar enough to their traditions. Islam shares many stories and teachings with Judaism and Christianity, and thus probably already contained elements of Zoroastrianism. As Persia transitioned between the two faiths, the local Muslims yet again absorbed some features of the older religion, resulting in the Shiite Islamic traditions of priesthood and shrines for saints, as well as the belief in a future savior.

Today there are still over 100,000 Zoroastrians worldwide, even though their faith is no longer a major world religion. A large population of believers still live in India, where they fled to escape conversion to Islam in the tenth century, and tens of thousands have also migrated to other countries such as the U.S., Canada and the U.K. However, today the religion is rapidly shrinking as more and more adherents intermarry with non-Zoroastrians, and the community is divided over whether to prioritize the continuation of the religion or the purity of their traditional culture.