Traditionally celebrated between 18 and 25 January (in the northern hemisphere) or at Pentecost (in the southern hemisphere), the Week of Prayer for Christian Unity mobilises countless congregations and parishes around the world.
Poland's largest Catholic publishing house has published a book, accusing Poles of profiting from the Holocaust by betraying Jews and stealing their possessions.
The death of Polish President Lech Kaczynski and an entourage in a plane crash in western Russia has united Poles as well as Christian leaders from the country.
A Polish sociologist has urged the Catholic Church to speak out in defence of the poor, after it was revealed as having the highest child poverty rate in the European Union.
A Polish Roman Catholic bishop who accused Jews of "inventing the Holocaust" has apologised and withdrawn accusations of manipulation against the news agency which published the interview.
The US President, Barack Obama, has abandoned controversial plans to site a missile system in Poland and the Czech Republic. The decision is likely to ease tensions in the USA’s relations with Russia.