The predominant political position of the Catholic Church is the way it uses its authority to push for open borders and mass Third World immigration into the West.
Pope John Paul II declared it a Catholic duty to be open to immigrants including illegal immigrants. The Catholic Church has an annual event called World Day of Migrants and Refugees. In 2002 John Paul II spoke under the title "To Overcome Racism, Xenophobia and Exaggerated Nationalism."
Jim Kalb analyzed this speech at Frontpage Magazine:
[The Pope] speaks of "undocumented migrants" as among "the most vulnerable of foreigners," of "the Christian duty to welcome whoever comes knocking out of need," of "true acceptance of immigrants in their cultural diversity," and of "Christ, who through us wishes to continue in history and in the world his work of liberation from all forms of discrimination, rejection, and marginalization."
[...]JPII was followed by Pope Benedict XVI, and Benedict continued the tradition of a Catholic World Day of Migrants and Refugees. The last event he gave this speech.
First, it appears that every country should have open borders. If they aren't open, some migrants will be undocumented and therefore become the special objects of hospitality and care. But if we have to welcome and care for them anyway, why not make it official and give all comers papers at the border?
Second, the flood of immigrants should be welcomed by local communities just as they are, and truly accepted in their cultural diversity. No boundaries of any kind may be drawn, because even the hint of a boundary would be latent discrimination. The Catholic Church should use its vast resources to inculcate such attitudes, and work with others to spread them through society generally. That, as all "social concerns" bureaucrats agree, is the prophetic function of the Church.
To which Lawrence Auster commented:
An example of what this leads to in practice is shown by this breakdown by religion of the Senate vote on the former U.S. mass immigration bill (S.2611). The Catholic senators voted 19-4 in favor of national suicide.