By David Willey
BBC News, Cologne
At the halfway mark in his first major foray abroad, Pope Benedict XVI has already made good on promises he made when he was elected last April, to reach out anew to other Christian believers and to Jews.
To Germany's Protestants he admitted that because of contradictory positions taken on ethical issues by different Christian denominations, all the churches were failing in their duties to believers.
"Our divisions disappoint the expectations of our contemporaries," he said.
First reactions to the Pope's visit have been positive
While pointing out continuing difficulties in the search for Christian unity, he expressed optimism for the future that practical solutions would eventually be found.
To Germany's Jews, Pope Benedict also offered continuing dialogue, after deploring what he called "the insane racist ideology" of Nazism.
In only the second visit by a pope in modern times to a synagogue, he prayed by the side of Cologne's chief rabbi for the six million victims of the Holocaust.
Pope Benedict has also sought to win the hearts and minds of the masses of young Christians from around the world who have flocked to the capital of Germany's Rhineland for the Catholic Church's World Youth Day.
This is also a recruitment campaign for the Catholic church of the future
He began his visit with a river cruise through the centre of the cathedral city first founded, as the Pope reminded his audience in one of his speeches, as a colony by the Romans.
Tens of thousands of young people waving the national flags of more than 100 countries massed on the broad banks of the Rhine to cheer the Pope as he acknowledged their greetings seated on the forward deck of a chartered tourist cruise ship.
The crowds of young pilgrims have been so dense that this city of one million virtually ground to a halt after the Pope's arrival. The central railway station had twice to be closed down when it could no longer contain the crowds.
The grand finale of the Pope's first visit to his homeland will be a papal mass at an abandoned open-cast coal mine nearly 30 km (20 miles) from Cologne's landmark cathedral. Church officials expect up to a million people to attend.
This is also a recruitment campaign for the Catholic church of the future.
With priestly vocations falling dramatically in many formerly Catholic but now increasingly secularised countries of old Europe, the Pope insisted on scheduling a meeting with seminary students training for the priesthood.
The crowds almost brought Cologne to a standstill
Germany, the country where the Reformation began, today has more Protestants than Catholics.
The most Catholic areas are the Saar, Bavaria and the Rhineland, in that order. In former East Germany the percentage of Catholics falls as low as 3% in Brandenburg and along the Baltic coast.
But the pews are emptying everywhere, just as in other parts of Europe. During the last decade the number of German Catholics regularly attending Sunday Mass has declined from 21% to 15%.
The Pope chose a theme for his first return visit to his homeland. He has referred in many of his speeches to the New Testament story of the kings from the Orient who came to worship the new-born Christ in Bethlehem.
Relics traditionally believed to be those of the Three Wise Men, brought to Cologne from Milan during the Middle Ages, are still venerated by pilgrims in the soaring Gothic cathedral.
First local reactions to the Pope's visit have been very positive. A Jewish leader praised the Pope for plain speaking "without ifs and buts". A local newspaper ran a headline: "He fills my heart."