A spokesman for AfD's chapter in the eastern state of Brandenburg confirmed Wednesday that Arthur Wagner left the party's regional board two weeks ago for "personal reasons". "Only afterwards was it known that he had converted to Islam", Friese told Reuters.
Founded in February 2013, the AfD focuses on so-called "soft" Euroscepticism, generally supporting Germany's membership in the European Union but slamming further European integration, unchecked immigration and the existence of the euro.
Kalbitz said there was "no pressure from the party" for Wagner to resign.
Wagner, who was once a member of German Chancellor Angela Merkel's Christian Democrats (CDU), joined the AfD in 2015, as the party began ramping up its anti-Muslim rhetoric.
Suddenly far-right officials stress in public religion is very much a "private matter".
According to the AfD, it states that "Islam does not belong to Germany" and "Islamic culture do not blend well in Germany".
For the far-right party, Wagner's conversion comes at an uncomfortable time.
The party's base consists mostly of staunch critics of Islam and immigration.
Also, the party calls for the dissolution of the Eurozone and opposes what the AfD describes as "the Islamization" of Germany. He told the German newspaper Tagesspiel that his conversion was "my business", refusing to comment beyond that. But as other possibilities for a deal with non-AfD parties in parliament have been unsuccessful, the Social Democratic Party has voted to begin coalition talks again.
It argued that increasing the number of Muslims in the country was a danger to Germany's state, society and values. "We have taken note of this development not without surprise", wrote Andreas Kalbitz, the AfD's regional head, before echoing previous remarks it was up to Wagner to make this decision. "Islam does not belong to Germany", it read.