Europe today is supposed to be a multicultural society in which diversities can coexist within a multicultural public sphere. But the realization of this objective requires new forms of legal equality and traditions of justice which are the main keys of understanding the demands of recognition that rise from the various communities in Europe. Different religious laws prescribe different days to accomplish religious duties and activities, and the Western calendar is still influenced by the legacy of Costantine’s religious policy. The approaches and goals of this paper are twofold. On one side considering the norms by which Constantine started the process of “Christianization” of the time of Western society; on other side evaluating to what extent the rules enacted in the Late Antiquity may still be considered as sources of inspiration for the “policies of time” in the contemporary public sphere. At any rate, both approaches aim to improve the effectiveness of religious liberty in a multicultural society.