(Demonstrators hold a poster opposing the visit to Germany by Pope Benedict XVI, during a protest in Berlin September 21, 2011/Thomas Peter)

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.