While the winds of an Iraq war are gusting ominously, peace advocates from across the religious and ethnic spectrum are joining forces. Pope John Paul II turned more than a few heads on Valentine's Day by hosting Iraqi Deputy Prime Minister Tariq Aziz at the Vatican and asking God to bless Iraq. But these two men share more than just a desire to avoid war: Aziz is a baptized Chaldean Catholic—Iraq's branch of Roman Catholicism.

Given the ruthless and bloody history of Iraq's Ba'athist regime, critics have questioned Aziz's Christian credentials. Still, the high profile of a Catholic in Saddam Hussein's overwhelmingly Sunni Muslim government has become a source of intrigue and curiosity. And it raises the larger question: How has Christianity fared in the history of Iraq—the geographic area that was once Mesopotamia? A few weeks ago we examined the origins of Iraq's Christian minority from Pentecost until Constantine's conversion in A.D. 312. Now we pick up their history from there.

Despite severe Persian Empire persecution, the ancient Mesopotamian Church blossomed during the fourth century while allied with Antioch, which was a major early hub of Christianity in the Roman Empire. In A.D. 410, at the Council of Seleucia, the Persian church declared its separation from Antioch.

Soon after, these Persian Christians fell under the influence of Nestorian teachings. Nestorius (d. 451), a patriarch of Constantinople, was condemned as a heretic by the Roman Church for leading his followers to question Jesus' dual nature as fully God and fully man. Many scholars of theology now believe poor Nestorius was more misguided than mischievous. He did not intend to separate the divine and human natures of Christ into distinct persons. But in his zeal to distinguish between those natures, he used unguarded language that led to his banishment and the persecution of his followers, who began fleeing the Roman Empire in the fifth century to seek refuge in Persia and Mesopotamia.

Over the next 600 years, the Nestorian Church developed into one of the most successful missionary-sending churches in all Christendom. Active in international trade, Nestorians spread as far as northern China. Their influence waned only when Islam gained regional dominance around A.D. 1000.

Islam first appeared on the Mesopotamian scene in the seventh century. Ironically, it got its first and biggest boost from a Christian.

At the time, the Persian Empire still exerted considerable influence. Persian ruler Chosroes II conquered Constantinople in 605 and by 615 and possessed every major city in the formerly Roman-controlled Middle East. But thanks to their leader's unquenchable lust for women, the Persians' Empire began crumbling by the mid-seventh century.

Despite his harem of three thousand wives and twelve thousand female slaves, Chosroes II demanded to have a woman named Hadiqah, the daughter of a Christian Arab named Na'aman. Na'aman stood up to Chosroes II because he wouldn't allow his daughter to marry a Zoroastrian. Chosroes II, enraged, trampled him with an elephant. Infuriated and emboldened after hearing the story, Arabs rose up and thoroughly defeated Chosroes II. The victory marked the beginning of a period of Arab assertiveness that culminated in the later Islamic conquests.

By 1000, an entrenched and powerful Islam had greatly curtailed the Christian influence in Persia and Mesopotamia. Already suffering from Islam's territorial and religious gains, the Nestorian Church was further weakened by internal dissent and corrupt church leadership.

But what really pushed Mesopotamian Christians into irrelevance was the thirteenth-century Mongol invasion of Genghis Khan. Khan had a Christian wife and was tolerant of Christianity. The Nestorians even tried to forge an alliance between European Christians and the Mongols against Islam that would open all of Asia to Christianity. But in the end the Mongols chose Muslim allies, and the Church in Mesopotamia and Persia faded from sight. The Christians who had once moved freely in Central Asia were now suppressed, indeed utterly exterminated east of the Kurdish mountains.

Roman Catholic missionaries did somehow reach Mesopotamia and Persia in the thirteenth century. These missionaries labored among the Nestorian Church remnant to restore doctrinal harmony. Finally, by 1553, facing new problems in Europe with the Protestants, the Latin Church gained new strength in the region by reconciling to itself some Nestorians. Thus was the Chaldean Catholic Church formed.

Based in Baghdad, the Chaldeans are today the largest Christian group in Iraq, with about 240,000 adherents as of 1995. The old Nestorian Church, now called the Assyrian Church of the East, claims about 60,000. The nation's two largest evangelical Protestant churches claim about 13,500 adherents. By David Barrett's estimate, many believers in the older churches have also been touched by the rapid spread of the Pentecostal/charismatic renewal.

All of these numbers would doubtless be much higher were it not for the bloody twentieth century. After World War I, Mesopotamian Christians initially benefited from the British Mandate by receiving special privileges. But when the League of Nations created an independent Iraq in 1932, Assyrian cities were burned and Christians killed for their ties with the former Western rulers.

In the 35 years since Hussein brought the Ba'ath Party into power, he has denied the separate religious identity of Iraqi Christians in an effort to construct a secular Arab nationalist state. He has tried to stamp out their Syriac language by banning it from many of the schools. In an effort to boost his Islamic credibility, Hussein has forced Christians to learn the Koran. And he has often lumped them in the same ethnic category as the Kurds, knowing the groups don't get along because of disputed land holdings in oil-rich northern Iraq.

With a history of world isolation, Iraqi Christians don't maintain much tolerance for traitors. So there's a reason the highest-ranking Christian in the anti-Hussein Iraqi National Congress calls Aziz the most hated man among Iraq's beleaguered Christians.

* For further information on topics treated here, albeit from an older and biased source, see the Catholic Encyclopedia (1913) on Chaldean Christians, Nestorianism, and the History of Persia.

* For statistics on Christianity in late twentieth-century Iraq, see David B. Barrett, "Iraq," World Christian Encyclopedia, Vol. I (Oxford University Press, 2001).