On September 11, 2001, two planes crashed into the Twin Towers, destroying them in their entirety. The images went around the world and sent shivers down the spine of the entire planet. The attack, allegedly inspired by religious fanaticism, killed nearly 3,000 people and injured another 6,000. Churches, synagogues and mosques were filled, and this time not to exact revenge. The entire area around the World Trade Center in New York, now restored as a memorial, was also destroyed. Was a concrete monument enough to reverse the disaster? The millennium began badly and things are no better in Gaza today. Here again, the religious inspiration is not clear, but they leave a reflection for the beginning of the millennium. Are we really facing a religious war at the beginning of the 21st century? 

Thirty-three days after the 9/11 attack, Jürgen Habermas received the national booksellers' award in Frankfurt's Pauluskirche on the utopian theme of peace. Contrary to the dominant voices that spoke of new wars of religion, the enlightened philosopher and neo-Marxist ("with little musical ear for religion," as he himself said) affirmed that the attack "had struck a religious chord in the innermost part of secular society. Moreover, he claimed that fundamentalism was a modern phenomenon, which owed more to ideologies than to religious principles (in this he agreed with Ratzinger, who thought that Islamic fundamentalism owed more to Marxism than to Islam, more to Capital than to the Koran). The philosopher of the Frankfurt School also maintained that the ethical foundations of the liberal state were of religious origin, albeit secularized and expressed in a rational sense.

Two and a half years after the attack on the Twin Towers, in January 2004, the famous meeting took place between Habermas and Ratzinger, the enlightened philosopher and the Bavarian cardinal, which gave rise to the so-called Munich Paper. It is now twenty years since that discussion. First of all, the degree scroll of the speech is significant: "Pre-political moral foundations of the liberal state". So we were not talking about politics, but about "prepolitics", about the ethical foundations of the political system. Moreover, a liberal society (i.e., what we usually call a democratic and pluralistic society) was accepted as a possible space for coexistence. There was no thought of a confessional State, of an identification between Church and State, as is still the case in some places. Thus, it is clear that the maxim "render to Caesar what is Caesar's, and to God what is God's" (Mt 22:21) is not easy to fulfill. Nor is it so today. The wars in which we see a cruel connivance between throne and altar confirm us in this sense.

Secondly, as we said, they spoke of "pre-political moral foundations": they did not refer to politics or to a particular ideological orientation, but to ethics and the foundations prior to the political game, according to the principles emanating from Christian thought, suggested Ratzinger. They were looking for common ground on which to dialogue, and in this there was an initial harmony between the two interlocutors, despite coming from different regions of the religious spectrum: a post-Marxist philosopher, albeit with a certain sensitivity to religious values, versus one of the most important theologians whose thought has emerged between two millennia. Ratzinger also showed a certain sensitivity to agnosticism and to those anonymous seekers of God in the fog. Two worlds faced each other, the believer and the agnostic. The meeting thus presented a certain stamp of prestige and prophecy.

Far from Pilate's skeptical and contemptuous question ("What is truth?": Jn 18:37), uttered dismissively while washing his hands, Ratzinger and Habermas both took this question seriously, starting from different conceptions. Although Habermas was a post-ideological thinker, he knew how to transcend the narrow margins of this Closed system of non-thinking, and sought to build a bridge with religious and, therefore, metaphysical thought. In this sense, the future German pope appealed to the "project of a world ethic"(Project Weltethos), for which Hans Küng had advocated, but gave it a new content. According to Ratzinger, however, the focus of the meeting was not religions but reason. For only in reason was there prior agreement . Thus, was a world ethic possible that could be shared by all, believers and non-believers, all of them, however, thinking? Was it possible to base values on simple consensus or, on the contrary, was a higher written request required, of which reason is its main ally? 

There, at the Catholic Academy of Bavaria, Ratzinger relied more on reason and science than on a Christian faith, not always shared by all. As Chesterton had said: the problem today is not so much the lack of faith, but the lack of reason... He did not renounce the truth, but neither did he impose it. Truth is proposed, but not imposed, although only "the truth makes free" (Jn 8:32). The Bavarian cardinal also appealed to law, which must be above individual interests and "the law of the strongest". In their own biography, Ratzinger and Habermas had seen how the Nazis tried to suppress the law by trying to subjugate judges. The law was no longer equal for all. This law was also to be combined with freedom: it was to be realized in a plenary session of the Executive Council, for law is not an instrument of power, but "an expression of the common interest of all. 

It was curious that a theologian should be speaking of the necessity of law. Perhaps the written request law is a corollary of the very existence of truth. The law cannot restrict or limit my freedom, but rather give it wings, help it to grow, direct it towards a good destination, in which to continue to grow in freedom. Apart from the criterion of the majority, what was needed was a reference letter common to all, a refuge in which all could take shelter. This is what we call truth, nature, human dignity or what Habermas calls - with a certain audacity on his part - imago dei, image of God. Thus, consensus was not a sufficient basis for human rights either, as is also evident today. It would therefore be necessary to overcome the crisis of law or natural law, also for our own sake. 

Yes, the Protestant theologian Johann Baptist Metz considered that Habermas could not simply be considered a "post-metaphysical" philosopher, while mentioning the scandalous stone: the question of truth. The difference between the two - Habermas and Ratzinger - was therefore clear: while for the philosopher truth is the fruit of dialogue, for the theologian, dialogue is the fruit of truth. While Habermas understood truth only as consensus, for Ratzinger it is the truth that precedes us, in which we are rooted and to which we can gain access through reason. In the current circumstances of expansionist caliphates and attacks on civilians in both directions, the question was not out of place. The pending question was whether, in the midst of this postmodern and post-secular environment, religion had a place. 

The 21st century will be metaphysical, religious, or it will not be, it is repeated in a somewhat emphatic way. In this line, Ratzinger and Habermas agreed that reason and religion could cure each other of their respective "pathologies". Yes, reason can cure religion from falling into fanaticism or fundamentalism, perfect alibis for killing in the name of God. But religion can also prevent reason from making mistakes like Auschwitz, Hiroshima or Chernobyl. "The dream of reason produces monsters," Goya painted. Reason without religion is also dangerous. They must help each other. For the time being, it would be enough if truth, reason, conscience, justice and a broad concept of nature, which is not limited to the environment, also had a place in the public sphere. The agreement reached by Habermas and Ratzinger twenty years ago on the basis of difference could shed some light on the present moment.