You can mix christian negroes with christian whites. It is seen in anglican churches. They mix well. You cannot mix christians or post christians with islam. In fact, you cannot mix anything that is not islam, with islam. Islam does not accept pork, alcohol, women dressing in skirt, people that do not do ramadan, relationship without marriage, relationship between muslims and non muslims. And punish transgression with violence and death. It is basically not compatible with western culture, as well as not compatible with asian culture.