From Think Progress:
The defining moment of former pizza executive Herman Cain's upstart presidential bid came in March when he told ThinkProgress that he would not be comfortable appointing Muslims in his administration. The exact question I asked Cain was: "Would you be comfortable appointing a Muslim, either in your cabinet or as a federal judge?" To which, he responded, "No, I will not." (Imposing a religious test is patently unconstitutional.)
Read more here.