"The Italian Republic, recognizing the value of religious culture and taking into account that the principles of Catholicism are part of the historical heritage of the Italian people, will continue to ensure, within the framework of the aims of the school, the teaching of the Catholic religion in non-university public schools of all levels" (Art. 9 §2 of Law 121/85). This article of the Agreement for the revision of the Lateran Concordat is the fundamental basis, but also the summary, of the reason why the Teaching of the Catholic Religion (IRC) is taught in Italian schools. Forty years after that agreement that modified the structure of the old religious, catechetical and non-scholastic teaching, in a teaching framed "in the purposes of the school", there is still a long way to go. The legal structure of the teaching of religion in schools, as outlined by the concordat and the numerous rulings of the Constitutional Court, gives us a weak disciplinary profile that between teaching practices that are not always well outlined, despite the excellent training of religion teachers, and the numbers of advalents that are not always high, especially in upper secondary school, push towards an increasingly marked religious illiteracy, which not only prevents the clear distinction between faith and religion, declassifying the latter, precisely by virtue of the link with faith, to something personalistic and unscientific, but limits the citizen in understanding cultural realities, often linked to religion, which now surround him. The aim of this paper is to retrace the history and legislation of Italian religious teaching and to attempt a correlation between the growing Italian illiteracy and the weak disciplinary assent of this teaching, proposing some improvement solutions.