According to Der Spiegel, the number of Germans converting to Islam has grown sharply. Between July 2004 and June 2005 about 4,000 German converted to Islam. that's about 4 times as many as the previous year. Der Spiegel looked at the numbers as part of a study for the German ministry of Internal Affairs that has just been published.
According to Salim Abdullah, spokesman for the Center for Muslim Archives is Soest the most important reason for conversion is the marriage of German women with Muslims. He emphasized that these conversions are not done under pressure. Additionally, about 300 German convert every year on their own initiative.
Imam Mohammed Herzog from Berlin (ed. who I understand is also a convert) confirmed that many convert had previously been Christians though they have had doubts for a long time about their religion.
The German religion-sociologist Wohlrab-Sahr emphasized that many felt an appeal to the "other side" of Islam. The current debate in Germany about Islam means more attention to Islam and this religion wins more and more a place in German society.
Source: RKniewus (Dutch)