If we don't allow him to keep bringing it up, then we have to stop theists from always bringing god up. We would have to stop atheists from always bringing up the idea that god doesn't exist. We would have to stop everyone from repeatedly bringing up their political views. Everyone here repeats their own beliefs and ideaologies in multiple threads. The only difference here being that Mehmet's beliefs are extremely unpopular.
Even if the open windows of science at first make us shiver after the cozy indoor warmth of traditional humanizing myths, in the end the fresh air brings vigor, and the great spaces have a splendor of their own - Bertrand Russell