The philosophy of the Enlightenment and political thought of modernity found tough opposition in the Roman Catholic Church. Liberalism was associated with Free Masons and revolutionary intent. Nonetheless, liberalism and political economy stimulated some theoretical analysis and specific theoretical positions in terms of social philosophy and social economics by the Church. This paper presents an analysis of encyclical letters and other papal documents, as well as the writings of other Catholic scholars, to elaborate on the theoretical points used to contrast liberalism. Compromises, as well as turning points in the evolution of the Catholic position, are investigated. Lastly, the epistemological and historical reasons for the affinity of Roman Catholicism with ethical liberalism and the limits of this similarity are discussed. 1. Liberal and Catholic, an Italian drama