As the Pope visits Jordan, Israel and the West Bank, he faces an combustible cocktail of issues combining relations between the world's three main monotheistic religions, one of the world's most intractable political conflicts and the legacy of the Holocaust. The BBC News Website looks at the areas of controversy he will have to navigate.
CATHOLIC-JEWISH RELATIONS
The Catholic Church has moved in recent decades to make amends for a long history of anti-Semitism.
In the 1960s it reversed its centuries-old policy of blaming the Jews for the death of Jesus and altered a prayer used on Good Friday which called for the conversion of Jews and described them as "faithless" - sometimes translated as "treacherous".
Pope Benedict XVI's predecessor, John Paul II, made efforts to improve relations. He spoke of growing up with Jewish friends in Poland and was the first Pope to visit both a synagogue and the site of the Auschwitz gas chambers.
It was under him that the Vatican, long seen as pro-Palestinian by many Jews, finally established diplomatic relations with Israel after the 1993 Oslo peace accords.
He made a historic apology for the wrongs done to Jews by Catholics over the centuries, and visited the Holocaust Memorial Yad Vashem and the Western Wall on his trip to the Holy Land in 2000.
But some Jewish groups felt he had not gone far enough, in not specifically mentioning the silence of the Vatican during the Holocaust.
Pope Benedict arrives with a more problematic background. As a young German he joined Hitler Youth at the age of 14, as was mandatory at the time. But he has since spoken of how his teenage years were "marred by a sinister regime". He later served in the German military, but deserted towards the end of WWII.
Two moves in the run-up to his visit have done little to build confidence with Jewish groups:
- In January 2009, the Pope lifted the excommunication of a bishop who had denied the Holocaust. Bishop Richard Williamson had disputed that six million Jews had died at the hands of the Nazis and said the gas chambers did not exist. The Vatican has since said the Pope was not aware of the bishop's views at the time, and the Pope later strongly condemned holocaust denial in an attempt to curb the damage caused by the row.
- Jewish groups were angered in October 2008 when Pope Benedict spoke in favour of advancing the process to make the late Pope Pius XII a saint. Pontiff from 1939 to 1958, Pope Pius is widely accused of failing to speak out during and after the Holocaust. The Vatican maintains he helped many Jews secretly. Pope Benedict has since called for a "period of deeper study and reflection" on the beatification process - widely seen as putting the process on hold.
- Pope Benedict also caused concerns among Jewish groups in 2007 by allowing a version of the controversial Good Friday prayer to be used more widely. He altered its wording in 2008, but it still calls for Jews to "recognise Jesus Christ, the Saviour of all men", a more explicit demand than was included in John Paul II's revised wording.
There is also a long-running dispute between the Vatican and the Israeli authorities over property taxes on Catholic buildings.
CATHOLIC-MUSLIM RELATIONS
The Pope also angered Muslims around the world during an academic lecture in 2006.
He quoted a 14th Century Christian Emperor who said the Prophet Muhammad brought "things only evil and inhuman", as part of a discussion on the issue of compulsion in religious conversion.
This sparked angry protests around the world, including firebomb attacks on a number of churches in the West Bank.
Pope Benedict eventually issued an apology, expressing sincere regret "that certain passages of his address could have sounded offensive to the sensitivities of the Muslim faithful".
He stressed the views he quoted were not his own. But for many Muslims, his apology did not go far enough.
However, he reversed some of the damage to his reputation among Muslims when he pressed ahead with a planned visit to Turkey and prayed facing Mecca in a mosque.
The following year, he reversed a decision to downgrade a Vatican department that deals with the Islamic world.
However, in Nazareth, where the Pope is scheduled to lead the biggest mass during his Holy Land trip, a small number of Muslims are opposed to his visit.
Media reports say leaflets have been distributed saying "a person who cursed the Prophet… is unwanted here", and a banner has been put up condemning those who insult the Prophet.
The town, which has a sizeable Christian minority, saw high tensions a decade ago over plans to build a large mosque opposite the church marking the spot where the Angel Gabriel is held to have informed the Virgin Mary she would give birth to Jesus.
LOCAL CHRISTIANS
Most of the Christians in the Holy Land are Palestinians living in the West Bank, Gaza or East Jerusalem, and Israeli-Arabs living in the north of Israel, particularly in and around Nazareth.
The population has been declining for decades because of emigration, although the numbers are difficult to track.
Figures from 1947 put the Christian population of what was then Palestine at 7.3% of the total. Now the Christian populations of the West Bank and Israel are both thought to be about 2%.
Roughly two-thirds of the world's estimated half a million Palestinian Christians now live outside Israel and the Palestinian territories, according to Bernard Sabella of Bethlehem University. In Jerusalem, he says the number of Palestinian and Israeli-Arab Christians has dropped to a third of its 1945 level.
The combination of Israeli travel restrictions, lack of economic opportunities and often better overseas connections than Palestinian Muslims, has led many Palestinian Christians to emigrate to countries such as Australia, the US, Italy and to Latin America.
The pressure of living as a minority within a minority - particularly amid tensions between the Muslim world and the West - particularly in the years after the 11 September 2001 attacks on the US - is also seen by some as factor.
Palestinian Christians in the West Bank want to see the Pope take a firm stand on issues such as access to holy sites in Jerusalem and the economic impact of the West Bank barrier.
West Bank Christians must apply for special permits to visit Jerusalem, while the West Bank barrier has made travel between Bethlehem and Jerusalem much harder, affecting Bethlehem's economy.
The Pope is expected to cross the barrier to visit Bethlehem, and to visit a Palestinian refugee camp there.
But even so, a group of about 40 Palestinian Christians has written to the Pope asking him not to come, fearing it would boost Israel's image and fail to draw attention to the plight of Palestinian Christians.
