See what aquinas has to say about islam
Despite the long title, the book itself is a rather short treatise (75 pages). it also includes a translation of pope leo xiii's encyclical letter aeterni patris where he praises and encourages the revival of thomism in philosophy. the text of on reasons discusses a series of issues that separate christianity from islam, such as the trinity, the incarnation, the crucifixion, the eucharist, purgatory as well as the relationship between divine and free will. the words of peter that all christians should be able to give a reason of their hope in christ serve as a governing backdrop to the discussion - conversion is not being attempted here, but merely a logical exposition from the christian point of view showing that it is not irrational to hold the tenants in question. the treatment as a whole exhibits the superb degree of reasoned argumentation that one expects from aquinas. this short little work, in addition to providing a concise summary of certain fundamental matters of catholic doctrine, is especially topical in these times of ecumenism and dialogue with the east.