US Secretary of State John Kerry was recently criticized by Defense Minister Moshe Ya’alon for approaching peacemaking in an emotional and messianic manner.After the ex-general was reminded of Israel’s need for American support, he issued a muted apology, but the concerns he raised are central to the internal Israeli debate, and their substance should be addressed.Peacemaking is, almost by definition, messianic. The idea that in a few months, or even years, it is possible to reverse the flow of human history, with its ingrained violence between tribes, nations and religions, and create trust and cooperation, requires deep faith. While replacing the horrors of war with compromise and mutual understanding seems like an entirely rational choice, in reality, success in reaching and sustaining peace agreements is the exception, rather than the rule. Efforts to convince warring groups to lay down their arms, agree to painful compromises and accept the risk of being caught unprepared by a deceitful enemy are grounded more in religious belief than in political reality.For would-be peacemakers like Kerry, the history of recent efforts in other conflicts should be sobering. The American experiences in Korea, Vietnam, Iraq and Afghanistan did not end in peace, and the same is true in war-torn regions such as Sri Lanka and Colombia. Israelis need only to look a few tens of kilometers across their borders to the brutality of Syria and Lebanon to see the all-too-familiar images of tribal and religious warfare, and the frequent results of messianic peace efforts.Yes, there are some important exceptions, and these are worthy of careful study and provide some cautious hope.The peace treaty signed by prime minister Menachem Begin and president Anwar Sadat in 1979, while not perfect, has been broadly implemented for over three decades – in sharp contrast to the previous 30 years of warfare and destruction. But the circumstances, including the ability of both leaders to take political risks, as well as the geography of the Sinai buffer zone, were very specific to this case.Outside of the Middle East, we have the examples of Northern Ireland, where the Unionist Protestants and Nationalist Catholics reached and have more or less honored the 1998 peace agreement. But here as well, the limited peace is based on rational interests, and there is little love lost between the two groups, as public opinion polls and ongoing friction demonstrate.Similarly, the much touted post-apartheid transition in South Africa is also attributable to an entirely unique situation, particularly the exceptional role of the late Nelson Mandela. The many efforts to duplicate these examples elsewhere, often infused with a strong dose of messianism and talk of hope, trust and reconciliation, have generally failed. Academics also have little to offer, and many of the personal peacemaking efforts of professors from social psychology, education and other disciplines, undertaken with enthusiasm, and messianism, have yielded minimal substance. The models based on transferring techniques used to sooth disputes within families or between neighbors in a small neighborhood do not succeed on a global scale – conflicts between nations and religious mini-states (such as Hamas or Hezbollah) are of an entirely different nature.While some individuals in a violent political conflict share human experiences in an environment far away from the bombs and destruction, there is no reliable mechanism for converting such personal contacts into the wider political arrangements required for a stable peace.Numerous peace dialogues, summer camps and joint education projects aimed at future leaders are run by well-intentioned messianists, but without sustained impact on the wider societies.Nevertheless, when would-be peacemakers such as president Jimmy Carter or John Kerry respond by calling for trust and highlighting the insanity of destructive wars, it is difficult to say no. They offer hope instead of despair; construction instead of destruction; optimism in place of pessimism. And if, as is often claimed, there is little or no risk, and if there is no agreement on peace, nothing is lost, their efforts and lofty rhetoric should be greeted with enthusiasm, rather than fear.But there are real costs and major dangers associated with a failed peace process based ultimately on faith and hope.For Israelis and Palestinians, the unripe Oslo agreements, engineered by messianists from Norway, were clearly counterproductive.Arafat’s campaign of terrorism that followed these agreements reflected the loss of Israeli deterrence and security capabilities as a direct result of the “peace process” and military withdrawal. Israel then exerted great effort to restore these capabilities, also at a major cost. As a result, when the dust settled, the core of the conflict and the mutual fears that sustain it had increased, and most people are understandably wary of repeating another round.Kerry and his team would be well advised to consider these issues carefully and to avoid too much talk about hope, trust and faith, particularly given the long history of warfare over the Holy Land. Instead, a practical and rational approach, based on mutual interests in conflict management and security, with gradual and matching steps for both sides, rather than the hype of dramatic breakthroughs, can produce success.The biblical image of beating swords into plowshares is messianic – the prophets Isaiah and Micah were addressing circumstances outside the realm of normal human history and politics. As aspirations for prayer and imagination, they provide inspiration. But this prophetic tradition and other forms of messianism should not be confused with earthly politics, based on concrete interests, and the necessary elements for survival in a lawless world.The author is a professor at Bar-Ilan University (founder of the Program on Conflict Management); and the head of NGO Monitor.