In 1929 in Italy is signed the “Concordato”, an agreement between the Italian State and the Catholic Church. We can find issues and questions that recall the period characterized by Constantinian politics and by the famous Edict of Milan. This article reconstructs some facts and discussions in which political thought and philosophical reflection are closely connected. In particular, it is interesting to analyse the views of Ernesto Buonaiuti, a priest involved in the modernist crisis at the beginning of 20th Century and a scholar in History of Christianity. His writings about Augustine, the Constantinian period and Gioacchino da Fiore suggest a vision of the development of the Christian religion within which it is possible to identify some turnaround moments in which religious sentiment, community life and liturgical traditions leave more space to theoretical reflection and to philosophical thought. In this light, the relations between Buonaiuti, the Church, by which he was condemned, and the fascist regime acquire a special meaning.
