The Christian religion and other religions can offer their contribution to development only if God has a place in the public realm, specifically in regard to its cultural, social, economic, and particularly its political dimensions. The Church's social doctrine came into being in order to claim "citizenship status" for the Christian religion. Denying the right to profess one's religion in public and the right to bring the truths of faith to bear upon public life has negative consequences for true development. The exclusion of religion from the public square - and, at the other extreme, religious fundamentalism - hinders an encounter between persons and their collaboration for the progree of humanity. Public life is sapped of its motivation and politics takes on a domineering and aggressive character. Human rights risk being ignored either because they are robbed of their transcendent foundation or because personal freedom is not acknowledged. Secularism and fundamentalism exclude the possibility of fruitful dialogue and effective cooperation between reason and religious faith. Reason always stands in need of being purified by faith: this also holds true for political reason, which must not consider itself omnipotent. For its part, religion always needs to be purified by reason in order to show its authentically human face. Any breach in this dialogue comes only at an enourmous price to human development.
Benedict XVI, Caritas in Veritate, 56.