This week’s interfaith conference in Madrid, sponsored by the Saudi King, may be inherently limited in scope — but that doesn’t diminish its capacity for trouble. Like the debate over Senator Obama’s proposal to enter into direct talks with the president of Iran, critics are put in the awkward position of opposing dialogue in favor of conflict. Why, ask proponents of dialogue, should we look a gift horse in the mouth.

The danger in interfaith dialogues, as in diplomatic ones, is the price of admission. The thing to watch will be not what is said but what isn’t. And whose interests are being served by the silence. Everything must be done to avoid a clash of views that might force a participating party to quit. Respective theological certitudes are off limits; Muslims cannot be asked to forgo their conviction that Mohammed received a final revelation from God, completing what Judaism began and, Christians believe, Christianity improved.

Jews cannot be asked to forsake the belief that the other monotheistic faiths are not, in any absolute sense, true, although they are closer to truth than paganism. There is some wiggle room: the Vatican declared in Nostra Aetate with great effect a “dual covenant” theology holding that God’s covenant with the Jews was still in effect alongside the broader covenant with all people through the church. But these conferences reach a lowest common denominator of common values under a banner that professes that all religions are essentially the same. However high-minded, they fail to reflect the core conviction of any of the individual faiths they claims to represent.

Such a conference could not take place in King Abdullah’s own kingdom, where clergy from non-Muslim world religions would not be welcome. The King has forged ahead, no doubt reacting to the climate after September 11, 2001, as well as to the rumblings from Iran threatening the Arab regimes. Spain was chosen, according to one report quoting a Saudi official, “because of its historical symbolism as a place where Muslims, Jews, and Christians lived under Islamic rule in centuries past.”

And there’s the rub. The product being sold, “tolerance,” exists in the mind of the believer. The Saudis, in this case representative of widespread Muslim opinion, see “tolerance” in the framework of a Muslim-dominated world. This may represent a great improvement over what the Saudi government sponsored MWL secretary, Abdullah Al-Turki, calls “the renegade terrorist gangs” based around Al Qaeda. After all, Qaeda pledges to convert or kill the infidel. Tolerance under Islamic rule promises a better future.

But is that agreeable to any non-Muslim? Certainly Muslims have every right to believe that, on Judgment Day, humanity will see the superior truth of their faith. But it’s hard to see the logic of their going into this kind of conference asserting a core belief in Islamic supremacism, particularly with a political or military component. Wouldn’t it be logical to check those arguments at the door?

Then there is the question of reciprocity, though it’s unlikely to be addressed at Madrid. Muslim nations want the West to treat Muslims the same as other citizens and Islam as any other religion. But they extend no such treatment to other religions within their own nations. No western nation would make its own tolerance conditional on reciprocity. But one danger in this conference is that “tolerance” becomes the strategy of escaping the need to speak with clarity on these issues.

The MWL, working through its affiliated International Islamic Relief Organization, has provided funding for Hamas. It has repeatedly denounced terrorism, arguing that Al Qaeda misrepresents Islam. But it excludes Palestinian perpetrated violence from its definition of terrorism in a way that allows for other violent Muslim movements to be considered legitimate as well. Terrorism is out and un-Islamic; but much of Islamic terrorism is not terrorism.

Meeting at Mecca in January of 2002 — four months after September 11 — Muslim scholars convened by the League declared that terrorism “covers all acts of aggression unjustly committed by individuals, groups or states against human beings including attacks on their religion, life, intellect, property or honor.” But they called acts by the Palestinians against the Israeli occupation a form of jihad and legitimate self-defense. They charged that “anti-Muslim media campaigns … following the September 11 attacks against the United States are being orchestrated by Zionist organizations … ” and blamed “Jews in Palestine” for the clearest example of “heinous terrorism.”

Yet Israel and the Palestinians will be off the table, even though it is of paramount interest to many participants if not as a central concern then certainly as a symbol of the clash between Islam and the West. Clarification on this point is apparently too explosive to be contemplated, even while the Muslim states are demanding, in the name of tolerance and international harmony, that speech critical of Islam be criminalized.

We’ll be hearing more and more of the case for meeting Muslims halfway, even at the expense of the defining principles of the Western tradition. What’s the worth of a cartoon in a Danish newspaper as compared with avoiding a wholesale conflict with the Islamic world? And we’ll be hearing less and less trenchant analysis of what is really afoot. Those are the dangers to the free world on the road out of Madrid.

Mr. Twersky is a contributing editor of The New York Sun.