For three decades, until the Treaty of Westphalia ended them in 1648, wars engulfed central Europe. The conflict became known as the Thirty Years' War. It ebbed and flowed as Protestants and Catholics killed each other, and kingdoms engaged in what we today would call "great power" rivalry.
Layers upon layers of religious and secular complications propelled rivalries and sent armies into battle, largely in what is now Germany. Sweden, France, Spain and Hapsburg Austria were all drawn into the fray.
To say that one factor dominated the Thirty Years' War might be an exaggeration, but the struggle between Catholicism and Protestantism lay at its heart. In the same way, the struggles and violence in the Middle East have many layers and complications, but the age-old conflict between Sunni and Shia Islam lies at the heart of what is happening.
That doctrinal religious interpretations should deepen power rivalries, foster terrorism, bring thousands of protesters into the streets and lead to proxy wars in Syria, Iraq and Yemen, and to government crackdowns in Egypt, Saudi Arabia and Bahrain, is difficult for the Western mind to fathom. We have long forgotten the Thirty Years' War, when religion meant fighting to the death, and have traded religion for other causes for war and mass slaughter.
Even after the Treaty of Westphalia, although countries fought ostensibly for secular reasons – territory, empire, economic gain – religion was woven into the justification for conflict, as between Catholic France and Spain, and Protestant Britain. Religion was certainly present in the civil wars of Ireland and the Low Countries.
The West, although it has interests to defend, oil and domestic security among them, is to some extent a bystander to a feud between Sunnis and Shiites that dates back to Islam's earliest days and remains profound today.
After the First World War, the Western powers of the day redrew the map of the Middle East, a map that no longer demarcates effectively the line between Syria and Iraq, because a militant Sunni movement, the Islamic State, sprawls on both sides of the line. IS despises Shiites, considering them heretics, and has little time for conventional Sunnis and their states either, believing them to have strayed from the true precepts of Islam.
So IS has dropped itself into the midst of Sunni-Shia doctrinal tensions and rivalry between Saudi Arabia, with its extreme Wahhabi version of Sunni Islam, and Iran, the world's largest Shia state. Theirs is a religious and secular rivalry that has been inflamed by the Saudi government's beheading of a Shia leader, Sheik Nimr al-Nimr.
Complications are inside each country, too. Saudi Arabia fears disruptions from its own Shia minorities. By beheading the prominent Shia cleric, the kingdom sent a message of defiance not only to Iran, but also to its own minorities. It also provided a distraction for its own citizens from recent cutbacks in government subsidies caused by the precipitous drop in oil revenues, for which the Saudis themselves are complicit.
Iran has more openness in its politics than Saudi Arabia, although that openness has severe limits. Nonetheless, hardline elements in the Revolutionary Guards and Basij paramilitary forces oppose the nuclear deal struck last year with UN Security Council permanent members plus Germany. Stirring up antipathy toward Saudi Arabia reinforces the argument that Iran is surrounded by dangerous foes and needs its nuclear program.
The successful negotiations on the nuclear pact caused consternation in Saudi Arabia, since the Saudis do not trust the Iranians to fulfill their part of the deal. That the United States would push these nuclear negotiations undermined Saudi faith that the Americans were still a steadfast ally. Similarly, the Saudis were shaken by the Arab Spring revolts that toppled regimes in Egypt and Tunisia without U.S. support for status quo regimes.
Now Russia has entered the fray, as have Western powers, including Canada in a small way, although Russia's interests and those of the West are not the same. As in the Thirty Years' War, outside powers have picked sides in internecine disputes and are sending in military forces with different objectives.
Negotiations toward ending the Syrian civil war, the geographic heart of the region's religious and sectarian conflicts, were to begin shortly. Success was always going to be a long shot. The eruption of Saudi-Iranian tensions, and the helplessness of outsiders to do much about them, just made the long shot longer.