For more than two years now, the U.S. government has barred me from entering the United States to pursue an academic career. The reasons have changed over time, and have evolved from defamatory to absurd, but the effect has remained the same: I've been kept out.

First, I was told that I could not enter the country because I had endorsed terrorism and violated the USA Patriot Act. It took a lawsuit for the government eventually to abandon this baseless accusation. Later, I reapplied for a visa, twice, only to hear nothing for more than a year. Finally, just 10 days ago, after a federal judge forced the State Department to reconsider my application, U.S. authorities offered a new rationale for turning me away: Between 1998 and 2002, I had contributed small sums of money to a French charity supporting humanitarian work in the Palestinian territories.

I am increasingly convinced that the Bush administration has barred me for a much simpler reason: It doesn't care for my political views. In recent years, I have publicly criticized U.S. policy in the Middle East, the war in Iraq, the use of torture, secret CIA prisons and other government actions that undermine fundamental civil liberties. And for many years, through my research and writing and speeches, I have called upon Muslims to better understand the principles of their own faith, and have sought to show that one can be Muslim and Western at the same time.

My experience reveals how U.S. authorities seek to suppress dissenting voices and -- by excluding people such as me from their country -- manipulate political debate in America. Unfortunately, the U.S. government's paranoia has evolved far beyond a fear of particular individuals and taken on a much more insidious form: the fear of ideas.

In January 2004, I was offered a job at the University of Notre Dame, as a professor of Islamic studies and as Luce professor of religion, conflict and peace-building. I accepted the tenured position enthusiastically and looked forward to joining the academic community in the United States. After the government granted me a work visa, I rented a home in South Bend, Ind., enrolled my children in school there and shipped all of my household belongings. Then, in July, the government notified me that my visa had been revoked. It did not offer a specific explanation, but pointed to a provision of the Patriot Act that applies to people who have "endorsed or espoused" terrorist activity.

The revocation shocked me. I had consistently opposed terrorism in all of its forms, and still do. And, before 2004, I had visited the United States frequently to lecture, attend conferences and meet with other scholars. I had been an invited speaker at conferences or lectures sponsored by Harvard University, Stanford, Princeton and the William Jefferson Clinton Presidential Foundation. None of these institutions seemed to consider me a threat to national security.

The U.S. government invited me to apply for a new visa and, with Notre Dame's help, I did so in October 2004. But after three months passed without a response, I felt I had little choice but to give up my new position and resume my life in Europe. Even so, I never abandoned the effort to clear my name. At the urging of American academic and civic groups, I reapplied for a visa one last time in September 2005, hoping that the government would retract its accusation. Once again, I encountered only silence.

Finally, in January, the American Civil Liberties Union, the American Academy of Religion, the American Association of University Professors and PEN American Center filed a lawsuit on my behalf, challenging the government's actions. In court, the government's lawyers admitted that they could establish no connection between me and any terrorist group; the government had merely taken a "prudential" measure by revoking my visa. Even then, the government maintained that the process of reconsidering my visa could take years. The federal court -- which issued a ruling recognizing that I have been a vocal critic of terrorism -- rejected the indefinite delay. In June, it ordered the government to grant me a visa or explain why it would not do so.

On Sept. 21, the long-awaited explanation arrived. The letter from the U.S. Embassy informed me that my visa application had been denied, and it put an end to the rumors that had circulated since my original visa was revoked. After a lengthy investigation, the State Department cited no evidence of suspicious relationships, no meetings with terrorists, no encouraging or advocacy of terrorism. Instead, the department cited my donation of $940 to two humanitarian organizations (a French group and its Swiss chapter) serving the Palestinian people. I should note that the investigation did not reveal these contributions. As the department acknowledges, I had brought this information to their attention myself, two years earlier, when I had reapplied for a visa.

In its letter, the U.S. Embassy claims that I "reasonably should have known" that the charities in question provided money to Hamas. But my donations were made between December 1998 and July 2002, and the United States did not blacklist the charities until 2003. How should I reasonably have known of their activities before the U.S. government itself knew? I donated to these organizations for the same reason that countless Europeans -- and Americans, for that matter -- donate to Palestinian causes: not to help fund terrorism, but because I wanted to provide humanitarian aid to people who desperately need it. Yet after two years of investigation, this was the only explanation offered for the denial of my visa. I still find it hard to believe.

What words do I utter and what views do I hold that are dangerous to American ears, so dangerous, in fact, that I should not be allowed to express them on U.S. soil?

I have called upon Western societies to be more open toward Muslims and to regard them as a source of richness, not just of violence or conflict. I have called upon Muslims in the West to reconcile and embrace both their Islamic and Western identities. I have called for the creation of a "New We" based on common citizenship within which Buddhists, Jews, Christians, Muslims and people with no religion can build a pluralistic society. And yes, I believe we all have a right to dissent, to criticize governments and protest undemocratic decisions. It is certainly legitimate for European Muslims and American Muslims to criticize their governments if they find them unjust -- and I will continue to do so.

At the same time, I do not stop short of criticizing regimes from Muslim countries. Indeed, the United States is not the only country that rejects me; I am also barred from Tunisia, Saudi Arabia and even my native Egypt. Last month, after a few sentences in a speech by Pope Benedict XVI elicited protests and violence, I published an article noting how some governments in the Muslim world manipulate these imagined crises to suit their political agendas. "When the people are deprived of their basic rights and of their freedom of expression," I argued, "it costs nothing to allow them to vent their anger over Danish cartoons or the words of the Pontiff." I was immediately accused of appeasing the enemies of Islam, of being more Western than Muslim.

Today, I live and work in London. From my posts at Oxford University and the Lokahi Foundation, I try to promote cultural understanding and to prevent radicalization within Muslim communities here. Along with many British citizens, I have criticized the country's new security laws and its support for the war in Iraq. Yet I have never been asked to remain silent as a condition to live or work here. I can express myself freely.

I fear that the United States has grown fearful of ideas. I have learned firsthand that the Bush administration reacts to its critics not by engaging them, but by stigmatizing and excluding them. Will foreign scholars be permitted to enter the United States only if they promise to mute their criticisms of U.S. policy? It saddens me to think of the effect this will have on the free exchange of ideas, on political debate within America, and on our ability to bridge differences across cultures.

Tariq Ramadan, a fellow at Oxford University, is author of "Western Muslims and the Future of Islam." He can be reached at [email protected]