The archbishop of Milan expressed this conviction at a congress on "Postmodern Religion" organized by the School of Theology of Northern Italy.
The congress Tuesday focused on the psychological, cultural and religious aspects of religion and New Age from a Christian perspective.
"It seemed opportune to us to propose a meeting, specifically in this city, which would question consciences, the sense of the sacred and of religion, and how it is perceived by an individualist mentality," explained Monsignor Giuseppe Angelini, president of the school.
The meeting highlighted what "religion a la carte" means: a postmodern form of faith, composed by individuals, completely subjective and far from Christian teaching.
Cardinal Tettamanzi said such a faith affects the sense of the sacred and of faith, oriented, as it is, strictly to the subjective dimension and completely detached from the Gospel.
Moreover, he emphasized the value and essential character of a religiosity that speaks to man and his conscience, and not to a "worship of self," so typical today.
"One can fall into the risk of proposing a model of religion and a practice of faith of a strictly expressive nature, which consists in expressing what each one feels in his interior," the archbishop added.
The cardinal warned that the dangers lie in the "subjectivist deviation of the new religious conscience."
Monsignor Angelini said he hoped that the congress would help bring "theology out of the marginalization in which the prevailing culture wishes to place this discipline."