The commentator Necla Kelek has become a symbol of the generation of Turkish-born Germans who have grown up under the tyranny of their "community". She has written several devastating books about the sufferings of young Turkish men and women at the hands of their elders, particularly the "foreign brides" imported into Germany to live in forced marriages, to whose plight the authorities turn a blind eye. Significantly, Necla Kelek spoke in support of Sarrazin at his book launch. Last month, she received the Friedrich Naumann Prize in the birthplace of German democracy, St Paul's Church in Frankfurt. There she spoke movingly of her hope that German Muslims will seize the chance of freedom, explicitly comparing them to the East Germans who had also found life in the West problematic. Responding to President Wulff's "Islam is part of Germany", she bravely declared: "Not sharia, not the unity of state and religion, not the claims of the umma to infallibility, not the segregation of man and woman: none of these must be allowed to become part of Germany. That would be a betrayal of freedom, of the constitution and of the Muslims who are experiencing individual freedom for the first time in history." 

What the Merkel government is doing, by embracing the ideas of Kelek and Sarrazin, is reversing half a century of multiculturalism. It required courage for Angela Merkel to change her mind, but she did so. On the issue of Islam, the lady was for turning.

What is also striking, however, is the response to Frau Merkel's volte-face of the self-appointed guardians of liberalism. Let me give just one example: Günter Grass. In a recent newspaper interview, he argued: "The West's moral voice lacks credibility." Is Grass voicing necessary self-criticism here, or is something else going on? Here is his evidence. The West has no right to deny Iran nuclear weapons because Hiroshima and Nagasaki are not seen in America as war crimes. Note that for Grass, the annihilation of the Jewish state, which Iran has explicitly declared to be its goal, is less important than the supposed hypocrisy of the US in confronting the events of 65 years ago. Past trumps present. Grass is obsessed with his idée fixe, that the victors of the Second World War have failed to follow the example of Germans like himself in acknowledging their crimes, such as the bombing of German cities. He insists that, because the Bush administration has not been prosecuted for war crimes in Iraq or Afghanistan, therefore "the Nuremberg trials retrospectively become a farce, granting right-wing extremists an argument they wouldn't have had". But it is he who gives that argument respectability, by placing the Nazis and their Japanese allies on the same moral plane as the US or Britain. Tellingly, Grass thinks neo-Nazis are less dangerous than "politicians in the democratic parties who make a big circus to win votes from the far Right — as in the Netherlands, with Islam enemy number one". In other words, he makes no distinction between the representatives and defenders of Western civilisation and those who are fundamentally hostile to it. Grass is happier denouncing democratic leaders, such as Bush or Merkel, than the mortal enemies of the West, whether Nazis, communists or Islamists. 

I am afraid that Grass, who fancies himself the conscience of Germany, has instead become the opposite: the voice of a nihilistic moral relativism. He and his kind are precisely those "enemies within" against whom Ludwig von Mises warned us. Western civilisation cannot be destroyed by a crisis of capitalism: only the enemies within can threaten it. The West needs its critics to be tough-minded and even to break taboos. But civilised debate presupposes a reverence for life, liberty and the law that ultimately derives from the knowledge that we are made in the image of God. Public opinion can only perform its vital role of providing the checks and balances if its leaders clearly distinguish between, as Karl Popper so memorably put it, the open society and its enemies. 

It was in the book of that title, first published in 1945, that Popper wrote: "We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant." An ideology that preaches intolerance as an article of faith is incompatible with the open society that Western civilisation has uniquely nurtured. If we are to preserve our freedom, whether in the marketplace or the public square, we must not delude ourselves that we can accommodate Mephistopheles, as though he were just another exotic product of multiculturalism. The death cult of Islamist terrorism, which negates everything the West stands for, is the latest manifestation of Goethe's devilish nihilist, "the spirit that always denies". We cannot integrate those whose only purpose is the disintegration of our civilisation.