While Nicholas of Cusa was known in his time as one of the great defenders of Pope Eugene IV, it is clear that this is not all that he was, and it is for his other, more speculative work, that he is now considered by many as one of the greatest thinkers of all time. Although we cannot say he fits perfectly with the modern world, his works still have much to offer which could interest and inspire us today. Indeed, his was very far reaching in his ideas, and for some of them, we might not have got to a time when they can be fully appreciated. His brilliance can be seen from many perspectives, such as his interest in the science and mathematics, where he was able to speculate upon the universe in a rather unique way (suggesting for example, that the earth is not the center of the universe, and the universe is filled with other life forms). Even more remarkable than his scientific theories, especially for his time, are his inter-religious theories; while he agreed with Pope Eugene IV (and that includes the role the Church has in salvation), he was able to look beyond the Christian faith, and to see other religious traditions as being representations of the same basic religious truth, with each religion pointing in various ways to the one truth known and possessed by Christians. This is not to say each religion is of equal value or worth; he believed that the founders of world religions were inspired by God, but the human equation got in the way, and led to various imperfections which need to be purified in order for the members of those religions to see how their faith and tradition ultimately points to what is found in the Christian faith. While he could be said to be an inclusivist, this is not exactly the best way to describe him. He believed that world religions had elements of value within them which could be brought into the Church itself (he believed world religions could become the foundations for many different religious rites within the Church, allowing the people of those different rites to develop their own ways of praise and worship, as friendly rivals, each trying to outdo each other in their devotion to God).
Yet, Nicholas was also a man of his times, and we must not forget that. What he experienced and saw often influenced the development of his ideas. In part because of the role of Islam in his world, he wanted to have a dialogue with Islam, one which was open and honest, able to present criticism and yet one which could appreciate what was good in the religion as well. Others around him wanted something else: they wanted a crusade. But he saw the horror of this. Nicholas had written with sorrow on the way religion is used for war. If religion is meant to inspire what is best within us, why does it also inspire some of our worst passions as well? Does it have to be that way? For Nicholas, he did not think so. Instead of fighting each other, causing even the best us to become like beasts and hurt so innocents in our rage, he wondered why we do not try to get to know those of other faiths, and actually try to find a way to work together, and see if we can overcome our diversity through charity.
It is important to realize that dialogue is not necessarily irenic. There will be disputes. There will be disagreements. One shouldn’t try to paint over differences, rather, one should understand why they exist, and this will allow one to know if the difference is necessary or accidental. And this mean one must be willingness to hear the criticism of others about their faith, and the willingness to engage that criticism (and that means there might be the possibility of some change which comes as a result of the dialogue, though it depends upon many factors, including whether or not the issue at hand is definitive in the faith in question or not). By dialogue, we appreciate more what is truly important about our faith, what is peripheral, and what really doesn’t belong. We are not expected, nor should we be expected, to give up what is important; but we need to know what is important and why it is necessary for our faith. Often that is difficult when we only talk amongst ourselves, but when we dialogue with others, we really get to understand ourselves and our faith better. An unreflective faith is a dead faith (of course, different people will reflect upon it in different levels; the point is that if we don’t reflect at all on our faith it is because we don’t find our faith that important, and that, of course, is the death knoll for faith). Thus, we see that for Nicholas, he believed dialogue required him to discuss Christ and his role in salvation, and to show how those who ignore Christ end up having something deficient in their faith.
Throughout his life, Nicholas tried to figure out the best way to engage others. Does one build upon what one holds in common with the other, and show how Christian doctrines can be implicitly found in the faith of non-Christians? This he certainly tried to show in his De Pace Fidei. But what does one do when that fails? His encounter with Islam might give us some answer. His irenic De Pace Fidei was written before his Cribratio Alkorani, and the tone and approach he takes within them can, at times, be seen as the difference between night and day. While offering an original and thorough criticism of the Koran, he still tried to be as irenic about it as possible. He tried to give every benefit of the doubt to the Muslim faith, and indeed, he points out how many Christian interpretations of the Koran are merely polemical and false. He pointed out that Christians should give a reading of the Koran following the same rules and allowances they have for their own Scripture. Not everything need be seen as literal, as for example, the description of paradise in the Koran (here Nicholas points out that this description was clearly written for the Arab people, and the text is metaphorical, using the kind of images which were needed to attract and inspire Muslims to do that which was good). Yet, he is also quite harsh when he discusses Muhammad and one can find many of the previous Christian indictments against him. Even then, he still allows for the possibility that Muhammad had some valid religious inspiration as well. In this way, while being critical of others, even harsh as he tries to show their errors, this does not mean he went against the insight1s which inspired the De Pace Fidei. One can read his later criticism of Muhammad as a validation of the general principles established in the De Pace Fidei. Recognizing the inspiration of God in the religious faith of others should inspire Christians even more to work for their clarification, to purify their faith and to show them the fullness of truth in Christ. This can mean, as Nicholas does here, one should look at the human element in the other religions and how they pervert the truth and can be a cause of scandal. We must have the spirit of charity and a willingness to learn from others, but in the same way, they need to be able to learn from us. Dialogue goes two ways, and only when it is open, and honest, allowing for the good and the bad to be discussed, can it offer any real fruit. When we discuss too much of the good or the bad, without a proper balance, then dialogue ends, and something else, something worse, takes its place (syncretism or hostility). And this perhaps is why Nicholas’ criticism of Islam ends up being one of his inferior works.
 See Nicholas of Cusa, Writings on Church and Reform. trans. Thomas M. Izbicki (Cambridge, MA: Harvard University Press, 2008) for a selection of his ecclesial writings which help explain why he got this title.
 We have yet to appreciate the revolution in mathematics, a revolution which we can see in his own works, and how it should apply to theology, although Nicholas has given us the foundation by which we can and should reorient ourselves even here. For example, his notion of God in De Li Non Aliud (on God as not other) as it unites to his ideas of the infinite should provide new ways to understand the relationship between God and creation, and perhaps change our views on what creation is and is not, and how everything in creation can be said, in relative degree, to be in the image of God (with humanity having a special way in which they represent God).
 De Docta Ignorantia II-12.
 He affirms this by having the Word say, “You will |all| find to be everywhere presupposed not a faith that is other but a faith that is one and the same,” Nicholas of Cusa, “De Pace Fidei,” in Nicholas of Cusa’s De Pace Fidei and Cribratio Alkorani. Trans. Jasper Hopkins (Minneapolis: Arthur J Banning Press, 1994), 38 (Chapter IV).
 This is proposes by having St Paul say, “Where conformity of mode cannot be had, nations are entitled to their own devotions and ceremonies, provided faith and peace be maintained. Perhaps as a result of a certain diversity of devotion will even be increased, since each nation will endeavor with zeal and diligence to make its own rite more splendid, in order that in this respect it may excel some other |nation| and thereby obtain greater merit with God and |greater| praise in the word,” ibid., 70 (Chapter XIX).
 Although I think Nicholas is too harsh in his criticism; it is good that he did take the time to read a translation of the Koran, but beyond that, he still relied too much on legends about Islam, and he didn’t take the time and effort to study Islamic sources to make sure his interpretations were valid. In this way his later work reads as a continuation of the polemical tradition, but nonetheless, one can still see sparks and insights in it which differ from other Western sources on Islam.