In this article, the bishop Fisichella sustains the fact that the tasks that belong to the fundamental theology must be rethought in modern terms, because the cultural context of nowadays is profoundly changed by the carthesian „cogito” and by the subjective dimension of the human knowledge, introduced by Kant. This cultural situation verifies itself especially in the Occident, where the fundamental theology makes huge efforts to reach an answer to some questions, as: „Who is the man?”, „What is nature?”, „Who is God?”. Even if this cultural environment is hard to define, the apologetics proposes with force the necessity of the truth and its relation with the truths of the Christian faith. Thus, the author shows that it is necessary to talk today about the truth, with a lot of passion, courage and love. But what truth are we talking about? We are talking about a truth that demands the identity of the subject that has to explain to an interlocutor why and how he has to speak about it. Thus, for a theologist, the truth has a face, and that face is Jesus of Nazareth. In the key of the modern philosophy, truth means love and liberty. But, nowadays, the question of truth implies the question of the true religion, therefore the relations between religions that, as corresponding to the teachings of the 2nd Vatican Council, must be characterized by respect and dialogue. Finally, the author invites everyone to search and to tend to the truth.