Pius X reversed the accommodating approach of Leo XIII towards secular governments, appointing Rafael Merry del Val as Cardinal Secretary of State (Merry del Val would later have his own cause opened for canonization in 1953, but still has not been beatified).
When the French president Émile Loubet visited the Italian monarch Victor Emmanuel III (1900–1946), Pius X, still refusing to accept the annexation of the papal territories by Italy, reproached the French president for the visit and refused to meet him.
That led to a diplomatic break with France, and in 1905, France issued a Law of Separation, which separated church and state, and which the Pope denounced.
The effect of the separation was the church's loss of its government funding in France.
Two French bishops were removed by the Vatican for recognising the Third Republic.
Eventually, France expelled the Jesuits and broke off diplomatic relations with the Vatican.

The Pope adopted a similar position toward secular governments in other parts of the world: in Portugal, Ireland, Poland, Ethiopia, and a number of other states with large Catholic populations.
His actions and statements against international relations with Italy angered the secular powers of these countries, as well as a few others, like the UK and Russia.
In Ulster, Protestants were increasingly worried that a proposed Home Rule Ireland run by Catholics inspired by Pius X would result in Rome Rule.

In 1908, the papal decree Ne Temere came into effect which complicated mixed marriages.
Marriages not performed by a Catholic priest were declared legal but sacramentally invalid, worrying some Protestants that the church would counsel separation for couples married in a Protestant church or by civil service.
Priests were given discretion to refuse to perform mixed marriages or lay conditions upon them, commonly including a requirement that the children be raised Catholic.
The decree proved particularly divisive in Ireland, which has a large Protestant minority, contributing indirectly to the subsequent political conflict there and requiring debates in the House of Commons of the United Kingdom.

As secular authority challenged that of the papacy, Pius X became more aggressive.
He suspended the Opera dei Congressi, which coordinated the work of Catholic associations in Italy, as well as condemning Le Sillon, a French social movement that tried to reconcile the church with liberal political views.
He also opposed trade unions that were not exclusively Catholic.

Pius X partially lifted decrees prohibiting Italian Catholics from voting, but he never recognised the Italian government.
Pius X reversed the accommodating approach of Leo XIII towards secular governments, appointing Rafael Merry del Val as Cardinal Secretary of State (Merry del Val would later have his own cause opened for canonization in 1953, but still has not been beatified). When the French president Émile Loubet visited the Italian monarch Victor Emmanuel III (1900–1946), Pius X, still refusing to accept the annexation of the papal territories by Italy, reproached the French president for the visit and refused to meet him. That led to a diplomatic break with France, and in 1905, France issued a Law of Separation, which separated church and state, and which the Pope denounced. The effect of the separation was the church's loss of its government funding in France. Two French bishops were removed by the Vatican for recognising the Third Republic. Eventually, France expelled the Jesuits and broke off diplomatic relations with the Vatican.
The Pope adopted a similar position toward secular governments in other parts of the world: in Portugal, Ireland, Poland, Ethiopia, and a number of other states with large Catholic populations. His actions and statements against international relations with Italy angered the secular powers of these countries, as well as a few others, like the UK and Russia. In Ulster, Protestants were increasingly worried that a proposed Home Rule Ireland run by Catholics inspired by Pius X would result in Rome Rule.
In 1908, the papal decree Ne Temere came into effect which complicated mixed marriages. Marriages not performed by a Catholic priest were declared legal but sacramentally invalid, worrying some Protestants that the church would counsel separation for couples married in a Protestant church or by civil service. Priests were given discretion to refuse to perform mixed marriages or lay conditions upon them, commonly including a requirement that the children be raised Catholic. The decree proved particularly divisive in Ireland, which has a large Protestant minority, contributing indirectly to the subsequent political conflict there and requiring debates in the House of Commons of the United Kingdom.
As secular authority challenged that of the papacy, Pius X became more aggressive. He suspended the Opera dei Congressi, which coordinated the work of Catholic associations in Italy, as well as condemning Le Sillon, a French social movement that tried to reconcile the church with liberal political views. He also opposed trade unions that were not exclusively Catholic.
Pius X partially lifted decrees prohibiting Italian Catholics from voting, but he never recognised the Italian government.
Pope Pius X