BERLIN (Reuters) - Pope Benedict starts his most difficult visit yet to his German homeland on Thursday, touring mostly Protestant and atheist regions in the ex-communist east after previous visits to Catholic strongholds in the Rhineland and his native Bavaria.
The country's religious and political complexity presents challenges for the 84-year-old pontiff, who is German but radically out of step with the way his homeland has developed, especially since its reunification in 1990.
Every word he utters during the state visit -- especially in his address to parliament in Berlin on Thursday or an Erfurt meeting with Protestant leaders on Friday -- will be weighed, analysed, hailed or slammed by his supporters and critics.
Benedict's predecessor John Paul always met rapturous crowds in his Catholic Poland. The pope from Catholic Bavaria can expect less deference from the Protestants of old Prussia or the atheist generations raised in communist East Germany.
But he has chosen to stride straight into the lion's den, addressing on his first day the Bundestag (lower house of parliament). About 100 deputies -- almost one-seventh of the legislature -- plan to boycott the speech in protest.
On his second day, he will meet Protestant leaders in the Erfurt monastery where reformer Martin Luther lived as a Catholic monk before posting the 95 Theses in 1517 that inspired the Reformation and split western Christianity.
PROTESTANTS WANT COOPERATION
The Protestants, whose ranks are roughly equal with those of German Catholics, want to celebrate the 500th anniversary of that event in 2017 with nationwide celebrations emphasising Luther's contributions to Christianity and German culture.
Their question now is how far the Catholics will cooperate.
Benedict is the first pope who really knows and understands Protestants. Will he speak of Luther as a heretic? Praise him for reviving Christian interest in the Bible?
Will he stress how important Luther's Bible translation was for the development of the modern German language.
German Protestants and Catholics will be listening carefully when he answers these questions in Erfurt on Friday.
Benedict will meet on Thursday with President Christian Wullf, a Catholic who has divorced and remarried in defiance of Church rules, and Chancellor Angela Merkel, a Protestant who has urged him to focus on improving ecumenical relations.
He also plans an open-air Mass on Thursday in Berlin's Olympia Statium, built for the 1936 Games meant to glorify Adolf Hitler's Third Reich, as well as meetings with Germany's Jewish and Muslim minorities.
After talks with Protestant leaders in Erfurt, he will travel to nearby Etzelsbach to meet a small Catholic community that defiantly withstood persecution under the communists.
Benedict will end his German tour in the mostly Catholic southwestern city of Freiburg.
(Reporting By Tom Heneghan)