Muslims in the Middle East are fighting wars of religion. Like the carnage between Protestants and Catholics that haunted Northern Ireland during the last third of the 20th century, there is little anyone can do until local peoples crave peace so intensely they are willing to cultivate it.

History shows that outside meddling only intensifies sectarian fury. Stopping internecine war begins at home. President Barack Obama imperils Americans by trying to excise an abscess that can be cured only from the inside out. The decision to re-engage in Iraq, and the wider Middle East, also contradicts the president’s other, bigger objective: to exit the nanny business.

The last time religious aggression swept an entire subcontinent was during the Reformation four centuries ago, when Christians hashed out their hatreds much as Muslims of the Middle East are doing today.

Islamic State, or as the president calls it, the Islamic State in Iraq and the Levant, is fighting to restore a caliphate. Catholics and Protestants spent decades warring over similar issues. Should all Christians accept the same religious doctrine? Should all nations be under the dominion of the pope?

The first Islamic Civil War, from 656 to 661, created two competitive sects – Sunni and Shi’ite. Neither recognized the other’s legitimacy.

Sunnis bowed to a caliph who ruled over all believers regardless of nationality. The last caliph was Sultan Abdülmecid II. Kemal Ataturk, the resolute builder of modern Turkey, fired Abdülmecid in 1924. The 400-year-old caliphate in Istanbul vanished.

Unsurprisingly, not everyone was happy about the rupture. In 1928, the Muslim Brotherhood began in Egypt. That group and other like-minded sectarian organizations gradually spread into the new secular nations of Syria, Jordan, Iraq and Iran.

Today, growing factions within the Sunni and Shi’ite populations wish to see their sects triumph and to replace secular with religious authority.

All were wrestling with the questions Catholics and Protestants brokered in Westphalia in 1648: Whether or not to burn, behead, shoot, or drown one another for apostasy, and whether to submit to a single religious authority.

The agreements reached in Westphalia followed 130 years of strife, including the defeat of the Spanish Armada in 1588, when Protestant Queen Elizabeth I of England beat back Catholic King Philip II of Spain’s rampage across Europe to put down heresy. Other rulers fomented mob violence with incidents such as the 1572 St. Bartholomew’s Day massacre in France, when the Catholic king targeted well-born Protestants. The king’s assassins murdered nobles in their beds while commoners knifed and strangled Protestant neighbors in the streets.

One-quarter of Europe’s population was killed during the devastating Thirty Years’ War (1618-48), another bloody phase of the Reformation. Brutal punishments included burning at the stake and pouring excrement down the throats of captives, a torture known as the “Swedish drink.” War spread famine and bubonic plague across Europe. Like now, greed complicated religious conflict, as combatants wrestled over lands and gold.

Exhausted, Protestants and Catholics finally agreed to negotiate. Gathering in separate towns, they sent messengers back and forth to avoid seeing one another’s despised faces. After five years of argument, the Peace of Westphalia concluded the tragic wars of religion. Separation of church and state took hold.

Religious or ideological battles typically aim to redraw boundaries and overthrow governments. Onlookers cannot end such conflicts — as Americans ought to know. Neither Britain nor France could stop the U.S. Civil War, which claimed 700,000 American lives, the most of any war the United States has engaged in.

Many of the Middle East’s religious sects are still so caught up in hoping some renegade faction kills off their enemies that they tolerate violence until it comes close to home — and then plead with the United States to come fix their mess. Plagued with conscience, Washington often responds.

Obama now promises, after committing to another foggy battle, to consult “allies abroad and Congress at home” within “two weeks.”

Washington needs a new strategy. One that puts the United States first and recognizes that other nations must bear responsibility for themselves and their own problems — especially internal ones.

As the Economist has noted repeatedly, countries like Iraq and Syria haven’t a hope of stopping Islamic State militants until they focus sharply on solving this sectarian struggle rather than fueling internal rivalries.

The United States can’t make them do this, as amply proved by Washington’s 11 years of vain collaboration with President Hamid Karzai in Afghanistan and eight years with President Nouri al-Maliki in Iraq, who built power at the expense of religious and ethnic opponents.

In the Middle East today, local leaders must decide whether peace is worth the price of costly compromises.

PHOTO (TOP): The Battle of Rocroi by Augusto Ferrer-Dalmau. WIKIMEDIA Commons

PHOTO (INSERT 1): Shi’ite Muslims attend Friday prayers at the Imam Hussein shrine in the holy city of Kerbala, June 13, 2014. REUTERS/Mushtaq Muhammed

PHOTO (INSERT 2): Elizabeth I. The portrait was made in approximately 1588 to commemorate the defeat of the Spanish Armada (depicted in the background) in 1588. Courtesy of WIKIMEDIA Commons.



PHOTO (INSERT 3): The capture of Maastricht in 1579 by Alexander Farnese, duke of Parma, by Jan Luycken in 1678. Amsterdam’s Historisch Museum. Courtesy of WIKIMEDIA Commons.

PHOTO (INSERT 4): Residents gather at a market destroyed during air strikes by the Iraqi military in the city of Mosul, June 28, 2014. REUTERS/Stringer