The social democratic parties did not monopolise the idea of solidarity in politics in Western Europe. The social democratic concept, both in its classic and in its modern version, was challenged from many quarters. Within the labour movement the communists insisted on regarding class as the foundation of solidarity and from outside the fascists agitated that the nation and the race should be the frame of reference for solidarity (see Chapter 8). The most permanent challenger in terms of solidarity, however, was to be social Catholicism and the political parties that saw Christian ethics as the foundation of solidarity.
As there is no plain road from socialist theory to socialist and social democratic politics, religious doctrines are not automatically reflected in Christian politics. Ideology –developed by Marxist and socialist intellectuals or popes, bishops and priests –is transformed into party ideology and politics through complicated processes. National history, cleavages in class structure and culture, political configurations, electoral considerations and other factors condition how and to what extent religion becomes an important factor in politics. In Western Europe religion has come to play a crucial role in politics in some nations, but not in others. Influential Christian democratic parties developed in Italy, the Netherlands, Belgium, Germany and Norway, but not in the United Kingdom, Denmark, Sweden and Spain.
In France, the Catholic Church had allied with the monarchy, and the revolution in 1789 initiated a long history of conflicts between the new secular state and the Church.