[6][7] The mosque is funded by Diyanet İşleri Türk İslam Birliği (DİTİB), a branch of the Turkish government's religious affairs authority,[8] bank loans, and donations from 884 Muslim associations.

[11] The developers have required that the secular areas of the mosque (e.g. the restaurant, event halls and stores) be open to people of all religions.

[12] The inauguration of the mosque in September 2018 during the state visit to Germany by the Turkish President Recep Tayyip Erdoğan was controversial as the Turkish-Islamic Union for Religious Affairs neglected to provide a satisfying security concept for the event.

[19] On June 16, 2007, 200 people gathered in a protest organized by Pro Cologne against the mosque including representatives from the Austrian Freedom Party and the Belgian Vlaams Belang.

[6][20] Then district deputy mayor Uckermann seconded that he thinks many residents reject the mosque because they believe that Cologne is a “Christian city”.

[21] Author Ralph Giordano stated that he opposed the project as the mosque would be “an expression of the creeping Islamization of our land”, a “declaration of war”,[19] and that he wouldn't want to see women wearing headscarfs on German streets, likening their appearance to “human penguins”.

It's a question of language and culture.”[5] Uckermann left the conservative CDU for right-wing Pro Cologne in 2008 after being voted out of office as the district's deputy mayor and reportedly facing party exclusion.

[22] The city's official for integration Marlis Bredehorst stated that "it is important that the Muslims here get dignified houses of prayer" and added that "two hundred years ago, the Protestants had to pray secretively in Catholic Cologne [...] that is something we can't imagine anymore today.

"[6] The city's mayor, Fritz Schramma, who supports the project said that “For me, it is self-evident that the Muslims need to have a prestigious place of worship, but it bothers me when people have lived here for 35 years and they don’t speak a single word of German.”[20] Christian leaders have taken similarly ambivalent stances: the Catholic Church has long supported the project, though recently Cardinal Joachim Meisner, Archbishop of Cologne, has been more cautious: when asked if he was afraid of the mosque, he said, “I don't want to say I'm afraid, but I have an uneasy feeling.”[13] He also stated that Turkey should allow its Christian minorities equivalent rights.

[8] Wolfgang Huber, Germany's top Protestant bishop, criticized the “male domination” he saw in Islam and said Muslims should be able to convert to Christianity without fearing reprisals[8] and the penalty of death.