The Judensau (Jews' sow) on mediaeval churches
The concordat alliance between Hitler and the Vatican was primarily directed to fighting communism, but the treaty partners also shared an antipathy to the Jews. Mediaeval tales of Jews poisoning wells were updated to claim that “Jewish Bolsheviks” were now poisoning society – and godless Jews, at that. These sculptures illustrate the Christian anti-Semitism that the Nazis were able to draw upon.
The Judensau (German for "Jews' sow") was a standard feature of mediaeval churches, especially in Germany. Over 25 of them still survive on German churches. During the Nazi period classes of school children were taken to see them.  Today the term Judensau survives as a neo-Nazi insult. 
This weathered sculpture of a Judensau is from the south façade of the Regensburg cathedral. It depicts three Jews, but the heads of two of them and the identifying pointed hats of all three have been knocked off. They are insultingly shown suckling from a sow – an animal they even refused to eat because it was “unclean”. (And, indeed, the pigs of mediaeval Regensburg rooted through the alleyways, living on garbage.)
The pagans of Europe had long since been christianised, but many Jews managed to resist the concerted attempts to covert them, which are prescribed in 15th-century Church canons.  In 1476 prominent Jews from Regensburg were accused of ritually murdering six Christian children. They were then subjected to seven, three-hour conversion attempts but, even in this threatening atmosphere, they held fast. The Jews were useful as “enemies”, whose presence could be used to foster Christian solidarity. They also served as convenient sources of money. The trumped-up ritual murder charges were used to justify charging the Regensburg Jews 18,000 golden pennies (gulden), which plunged the whole community into poverty. 
The Judensau sculpture was placed on the side wall of the cathedral which faced the Regensburg ghetto in order to mock the Jews who lived there. But the Church didn’t confine herself to ridicule alone. Every year, after a rousing Good Friday sermon about “Christ-killers”, the faithful would spill out of the cathedral and storm the ghetto next door. Excavations of the ghetto's cellars have revealed secret doors from one house to the next to help the terrified Jews escape their tormentors. ...The number of German Jews who were blonde suggests what must have happened to many Jeiwsh girls.
The year after the Regensburg charges of ritual murder, the persecution spread to Passau, just 120 kilometres downstream on the Danube. A woodcut, the scandal sheet of the time, tells the tale. A Christian was said to have stolen some Hosts from the altar. These were the wafers that, when blessed, became, according to the Church the body of Christ. The story claims that the thief sold it to the Jews, who took it to their synagogue below the cliffs by the river and there they pierced it with a stake in an attempt to kill Christ. The second half of the woodcut is factual. It shows what was done to the Jews. Some Jews were killed outright, others tortured to death, still others driven out and the rest baptised. The synagogue was torn down and replaced by the church of St. Salvator. The stake alleged to have been used became a holy relic.
Upstream from Passau in Regensburg, where the Judensau can still be seen on the facade of the cathedral, a plaque was reluctantly installed in 2005 – in German only. It sounds somewhat less than repentant: “This sculpture needs to be seen in its historical context”. 
It seems a bit impolite to ask which all-powerful institution in mediaeval Europe created this “context”. And even less polite to ask what this carefully-fostered hatred of Europe’s only non-Christian holdouts finally led to….
1. According to an elderly parishioner attending church in Cadolzberg in July 2003, during the Nazi period schoolchildren were taken to see the Judensau in the cathedral (Münster). This indicates that the surviving example on the outer city gate was not the only one in town.
Wolfram Kastner, "Feuerwehr löscht das Wort 'Judensau': Die staatliche Sau-Skulptur bleibt ohne Kommentar", haGalil.com ("the largest Jewish online magazine in German"), 5 August 2003. http://www.klick-nach-rechts.de/gegen-rechts/2003/08/judensau.htm
2. In Nazi parlance Judensau means "Jewish sow", which deftly turns the name of the sculpture into a slur. But to argue, as the Wikipedia article does, that therefore the Nazi use is "historically separate and morphologically opposite" is naive at best. As the school tour(s) demonstrate, the Nazis were eager to foster this tradition and a slight semantic shift to make the word more "useful" to them is hardy proof of any separate development. That's just the way language works.
3. See "[Decree on Jews and neophytes] ", Council of Basel 1431-45 A.D, Session 19, 7 September 1434. http://www.papalencyclicals.net/Councils/ecum17.htm
4. "Zunehmende Unterdrückung", Judentum in Regensburg, Wikipedia. http://de.wikipedia.org/wiki/Judentum_in_Regensburg#Zunehmende_Unterdr.C3.BCckung
"A Medieval Trace of German Anti-Judaism", Deutsche Welle, 1 April 2005. http://www.dw-world.de/dw/article/0,,1537282,00.html
See also: "Vatican raps politician over remarks", Ruth Ellen Gruber, JTA (Jewish Telegraphic Agency), 17 December 2008. http://jta.org/news/article/2008/12/17/1001635/vatican-criticizees-politician-over-remarks
ROME (JTA) — The Vatican criticized a leading Italian politician who suggested that the Church bore some responsibility for fascist-era anti-Semitism in Italy.
Vatican Radio on Wednesday called the previous day’s statement by Gianfranco Fini, the president of the Chamber of Deputies, "unfounded accusations." And the official Vatican newspaper l’Osservatore Romano accused Fini, who started his political career in the neo-fascist movement, of "miserable political opportunism" and "historic approximation."
At a ceremony in Parliament marking the 70th anniversary of the imposition of fascist anti-Semitic racial laws in Italy, Fini said Italians in general as well as the Catholic Church, not fascism alone, bore some responsibility for the fascist-era persecution of Jews.
L’Osservatore Romano wrote that fascism was solely responsible for "the infamy of the racial laws" of 1938."