When Wolfgang Schäuble convoked a multi-year “Islam Conference” in 2006 to ease relations between German society and its Muslim minority, the interior minister made a statement – “Islam is a part of Germany” – that was viewed as a groundbreaking and generous concession. Today it looks more like a statement of the obvious. At the final session of the conference on Thursday, the Federal Office for Migration and Refugees (BAMF) released a study on “Muslim Life in Germany”. It found that there are vastly more Muslims in Germany than most specialists and pundits had assumed. Where most estimates held the Muslim population at around 3m, the more comprehensive BAMF study places it around 4m, and possibly as high as 4.3m. That means Muslims make up not 4 per cent of the population, but 6 per cent. Does this matter? Of course it does. The new numbers are grist to the mill of those who say the authorities have not been straight with them about the scope of immigration. More important, the size of a community affects a country’s options for integrating it. The bigger it is, the harder it is. Against this, the BAMF study offers one basic reason for optimism: diversity. We should think not of a monolith of millions of like-minded newcomers but of a mosaic of communities, 10,000 here, 10,000 there. If Germany’s Muslims cannot agree among themselves, then how, in the end, can they develop a loyalty or allegiance to anything other than the German state? The multi-facetedness of German Muslim life is an implicit rebuttal of the sense that Muslims are “taking over”. Christopher Caldwell reports.