Diversity is a problem everywhere it is tried. The more homogeneous a society is, not talking about race or religion, but about central values and mores the less crime there is. Look at Japan. Not saying there is no crime in a homogeneous society but there is less. In a homogeneous society everyone knows what is acceptable and there is an unspoken agreement to work towards the welfare of all within the society. Where there is diversity of cultures there is no sense of unity.