Editor's note: Paul Moses is the author of a new book, "The Saint and the Sultan: The Crusades, Islam and Francis of Assisi's Mission of Peace." (Doubleday, 2009). He is a professor of journalism at Brooklyn College and the CUNY Graduate School of Journalism.
New York (CNN) -- Evangelical Christian leaders such as Pat Robertson have assailed President Obama's effort to engage Iran, and the results so far have not vindicated the president's approach as a diplomatic policy.
But if these leaders' goal is to bring Christian attitudes into the realm of public policy -- which, of course, is what they have called for time and again -- they might just as well be thanking the president for his new strategy. That is what the experience of one of history's greatest Christians, Francis of Assisi, teaches us.
Francis engaged Christendom's enemy, Egypt's Sultan Malik al-Kamil, by approaching him unarmed in the midst of the Fifth Crusade in 1219. The Crusaders had laid siege to Damietta, a city at the mouth of the Nile where 80,000 people were dying of disease and starvation.
The Christian forces were hoping to conquer Egypt, which would not only make it easier to take and hold Jerusalem but would deal a heavy blow against all Islam.
Francis actually believed what Jesus said in the New Testament about loving his enemy and took a much different approach than his fellow Christians.
His goal was to convert Sultan al-Kamil to Christianity through peaceful persuasion. He didn't succeed in that, but, amazingly, the two men found common ground and appear to have genuinely appreciated each other.
The sultan, who no doubt viewed Francis in light of an ancient Muslim tradition of reverence for holy Christian monks, permitted him to stay in his camp for several days, preaching the enemy's faith in the midst of the Crusade.
Francis was so influenced by the unexpectedly tranquil encounter with the sultan that when he returned home, he attempted to revise his order's code of conduct to urge that his friars live peacefully among Muslims and "be subject" to them as a way of giving Christian witness -- a revolutionary approach, considering that the Crusade was still being fought.
Francis' journey to the sultan's camp on the east bank of the Nile should be viewed as a mission of peace, since the sultan's conversion might have led to the end of the Crusade.
Francis, it should be said, was a tireless advocate of peace, a stance that stems from the trauma he suffered as a soldier and prisoner of war when he was a young man who saw his comrades massacred on the battlefield.
Since discussion of war and peace is -- even today -- so tinged with religion, it may as well be based on authentic religion. Francis represents what it means to be an authentic Christian. As Pope Pius XI wrote in 1926 on the 700th anniversary of Francis's death: "There has never been anyone in whom the image of Jesus Christ ... shone forth more lifelike and strikingly than in St. Francis."
I don't mean to liken Obama to Francis; there are few human beings in any era who would benefit from comparison to the saint of Assisi. In any case, their situations are very different. Francis was unarmed and powerless when he approached the sultan; there was no hint of coercion.
Obama, on the other hand, is arguably the most powerful person in the world. He can disarm his rhetoric, but it would not be possible for him to approach an enemy in the same powerless way Francis did.
Still, Francis' example tells those who call themselves Christian that they should refrain from weaponizing their words and should seek peaceful solutions whenever possible.
An organization called Charter for Compassion is taking this approach. Gathering together supporters such as Archbishop Desmond Tutu, the Dalai Lama, singer Paul Simon and Sheikh Ali Gomaa, the grand mufti of Egypt, it has sought to restore compassion as the center for morality and religion. It calls for a "return to the ancient principle that any interpretation of scripture that breeds violence, hatred or disdain is illegitimate."
Obama, too, touched on the role of authentic religion in his Nobel Peace Prize speech on December 10. Citing both the World Trade Center attack and "the cruelties of the Crusades," he said, "Such a warped view of religion is not just incompatible with the concept of peace but the purpose of faith -- for the one rule that lies at the heart of every major religion is that we do unto others as we would have them do unto us."
Nearly 800 years ago, at a time when biblical passages were used to justify the Crusades, Francis of Assisi sought a return to true New Testament values. Whether through his famous love of animals or his stunning visit to the enemy in the midst of war, Francis helps us to remember that startling acts of compassion are sometimes the best way to stir hearts and minds.
For those who want to be guided by what Jesus would do, Francis of Assisi is a good place to start.
The opinions expressed in this commentary are solely those of Paul Moses.