Men, observes Blaise Pascal, never do evil so completely and cheerfully as when they do it from religious conviction. The events of 9/11 seem only to prove Pascal right; the 19 hijackers saw no contradiction between having faith in God and the killing of innocents.
In fact, their faith seemed to have motivated the view that the ends always justified the means, even if it meant inflicting horrendous suffering.
This year, the site of the Twin Towers once again revealed the bitterness, hate and distrust that al-Qaeda engendered on 9/11. A Muslim group had announced its intention to build an interfaith centre and mosque two blocks from Ground Zero.
Many were concerned that the mosque would symbolise the triumphalist ethos of Islam.
Admittedly, those behind the Ground Zero mosque are peace-loving folk who are genuinely interested in building bridges.
However, there have been many who claim that Ground Zero is hallowed ground, much like Mecca - where churches, synagogues and temples are virtually non-existent.
Similarly, it is argued that Muslims should respect Ground Zero and refrain from building a mosque in its immediate vicinity.
A number of leading politicians in the US have made a similar argument, although, in more vociferous terms. For instance, Newt Gingrich, a former Speaker of the United States House of Representatives, noted that the mosque should not be built, since "Nazis don't have the right to put up a sign next to the Holocaust Museum in Washington".
Presumably, Mr Gingrich doesn't see any distinction between Muslims and Nazis. On the other hand, Michael Bloomberg, the son of Jewish migrants and the Mayor of New York, came out in support of the planned mosque.
I feel that Ground Zero is sacred, it is not a sacredness that is reverential in nature, but a sacredness that emerges from the sense of loss associated with 9/11.
It is the kind of loss that Holocaust survivor Elie Wiesel had in mind when he wrote, "Let us remember the heroes of Warsaw, the martyrs of Treblinka, the children of Auschwitz. They fought alone, they suffered alone, they lived alone, but they did not die alone, for something in all of us died with them."
Ten years on from 9/11 we know Bin Laden is dead, although the war on terror continues without any real end in sight.
There does appear to be a silver lining, however; the Muslim world is changing for the better despite al-Qaeda's best efforts.
I am an optimist, and I believe the heartlands of Islam are experiencing the kind of change that may prefigure a dramatic cultural, social and philosophical enlightenment. I use the term "enlightenment" deliberately, and I do this because I have lost count of the number of times I have been challenged, and questioned, on whether the Muslim world is capable of a true enlightenment - the kind that Europe experienced in the 18th century. In response to these challenges, I would usually argue that the Muslim intellectual heritage actually helped to motivate aspects of the European enlightenment.
Then there would be the follow-up question, "why is so much of the Muslim world today so far behind?"
This was a good question, and one I had great difficulty answering as it exposed an uncomfortable truth. Sure, the Muslim world has a long list of great achievements, but most of these successes happened 1000 years ago.
As of February 11, 2011, however, I have a new perspective. That is the day Hosni Mubarak resigned, and the people of Egypt were heard.
The people of Egypt found their voice; moreover, Tahrir Square, the pulsing heart of the protest movement, drew together Christians, secularists, Islamist, liberals, conservatives and even a Google executive.
The gathering in Tahrir Square cut across religious, political and social divides - the protesters wanted democracy, freedom and liberation from the old and entrenched. At the height of the protests, Tahrir Square resembled Mecca - with people gathered in their thousands around a central focal point. The brief resemblance to Mecca foreshadows something deeper - we saw a turn away from autocracy and autocratic systems. There was a turn toward openness, toward freedom of expression and freedom of thought.
As we remember the tragedy of 9/11, we should guard against the temptation to wallow in bitterness, distrust and hate.
Let us resist the temptation to be indifferent to the humanity of others, lest we prove Pascal correct once again.