I have never considered a link between atheism and racism. I also don't see Islam as a race. As mentioned above most muslims are not Arabic so obviously Islam tranceds race. I don't see anything wrong with saying that a particular cultural group does things I disagree with regardless of how large or small that group may be. Since this is based in behavioural patterns not racial aspects. For example; if you come from a culture where animal cruelty is ok- I am intolerant of that aspect of your culture; and I make no apologies for that.

For me the key is - does this behaviour cause harm.

I think part of the problem is we often use the same words for country, race and culture. For example French. A person may be racially French but brought up in another culture and not 'behave' in a French way.