YNet News:

A German official on Saturday called to stop Muslim immigration into the country, stirring public controversy.

Horst Seehofer, leader of the Christian Democratic Union Party (CSU), which is a member of the coalition government in Germany, said in an interview to Focus magazine, "It is obvious that immigrants from Turkey and Arab countries face more difficulty integrating into German society than other immigrants."

"In any case," Seehofer added," the conclusion is that we don’t need additional immigrants from 'foreign cultures'." 

...During the interview, Seehofer also argued that unemployment benefits should be revoked from immigrants who do not seek employment, arguing that immigrants should be forced to share the basic values of Germany, and have command of the language. 

According to the conservative politician, tolerance and openness to other religions, as cemented in the German constitution, do not grant these religions direct influence over the country's core values.
Seehofer's remarks angered politicians from across Germany's political spectrum, leading some politicians to dub him a "radical-rightist populist."

I don't see how this could be made. In most Islamic countries, people cannot change their religion from their own national identity papers. So, if someone is indeed like a Kuwaiti who converted to Christianism, but he is indeed considered as a Muslim in his country, what would they do?
I agree that, given some data, there is an important percentage of Muslims who are not easily integrated. Couldn't their permits being revoked when it's seen that they are not? Because it's clear that there are people who after preaching Jihad, etc. are not sent back their home countries immediately. (*)

What the German Govt (and politicians in general) have to consider is if agreeing to give Turks visas easily is actually the best way to solve the integration problem.

(*) I don't understand either why imams are not obliged to use the language of the place they are preaching. There are some of them who, after living 3, 10 even 15 years, don't know how to speak in the tongue used where they live.