The paper is concerned with cultural, religious and philosophical analysis of the Brazilian constitutional legislation. The dynamics of change of the constitutional provisions related to religion through the transforming role of the Catholic Church is shown. The texts of Brazilian Constitution of 1821, 1934, 1946, 1967/69 and 1988 are analyzed. The comparative characteristic of the Brazilian Constitution of the Empire and the Republic is conducted from the religious viewpoint. Basing on the analysis of the separation of church and state in constitutional legislation, an attempt to demonstrate relationship between religion and politics in the public arena, that requires a more complex understanding, beyond theoretical models of secularization and the separation of church and state is taken. Some writers’ opinion on the legitimacy of religious involvement in politics and in a democratic process in a secular society is presented, contesting that this activity may be incompatible with democratic and human rights guarantees.