in britain, the man on the left is muslim but the man on the right is white non-muslim  if you look like the man on the right you won't automatically be assumed to be a muslim. in fact you'll be thought of as some more swarthy type of white like a cypriot or a spaniard, but you won't automatically be assumed to be a "muzzie". this is because british people associate islam with pakistanis and indians only. anyone who is south asian is deemed a muslim by default. even hindus get called "paki muslim" by brits. however, if you're arab, middle eastern, levantine, nafri etc there is not an automatic labelling of "muslim" applied to you. you would literally have to tell brits clearly that you are a practicing muslim even if you have an islamic name. i know this because i look like the guy on the right and everyone assumes i'm non-muslim. i have to look overtly muslim to be known as muslim.
United Kingdom