A significant role, but not quite as much as sometimes thought.

In Catholic-Soviet Bloc relations, from 1947 and the Italian election when Catholic support of anti-communists gave Eastern Europe's 'Little Stalin's' the excuse to crush the freedom of Catholic worship,especially in Czechoslovakia, through until 1956 the Catholic church focused upon protecting its institutional rights, that is, the right of the existence of the Church property as an independent place of worship and other rights of its independence flowed from this core position such as the freedom of belief for its members and the right to control its own property. There was variation between the Eastern European nations, with Poland maintaining some independence for the church, Romania, Hungary and E. Germany choosing to submit to state control of the Church's assets and church structures being largely eliminated in Czechoslovakia.

After the Hungarian Revolution in 1956, the Polish church managed to regain a little of its independent role in society, due to the role it played in negotiating between the anti-Stalinist factions and the government and in avoiding a similar revolution.

The key change occurred at the highest level of the Catholic Church during the Papacies of John XXIII and Paul VI, as part of the discussions around and move towards the Vatican II ecumenical council. Through the papal encyclicals that emerged from this set of conferences the church's position changed from one of defending its fairly narrow institutional interests to a broadly based defence of human rights in general.

It was this intellectual position that helped the Polish Catholic Church act as an umbrella organisation linking, and showing limited support for, the various dissident organisations in Poland that began to emerge in 1976, before the appointment of John Paul II in 1978, and before the crucial moment of the Solidarity movement in 1980.

John Paul II may not have created the intellectual shift that led to the changed position of the Church, but as someone who had spent much of the previous 25 years living within a communist regime he was extremely well placed to see to the practical tasks of its implementation, providing a clear figurehead for independent society and human rights in the Soviet Bloc and mobilising millions in his various visits to communist states in the 1980s.

This combined with secular forces moving towards a human rights defence such as those who relied upon the 1975 Helsinki accords to form a powerful group who argued not explicitly for either communism or capitalism, but that fundamental humanity must be respected by political leaders everywhere. In Latin America this had the consequence of the Catholic Church supporting leftist groups under the 'Liberation Theology' banner in protest against authoritarian regimes, arguably expanding the intellectual Cold War in this area, but the net worldwide effect was certainly a positive one.

Thus the 'John Paul II ended the Cold War thesis' that some have advanced is doing disservice to his predecessors, and the Church as a whole, but it was an important factor along with ideas of secular social democracy and the mundane wish of many in the Soviet Bloc by the 1980s for greater material advancement in leading to the collapse of these regimes in 1989 and the beginning of the end of the Cold War.