Which always brings this to my head since they love to tell us we can't wear Western clothes since it makes us look like an unbeliever. My answer is: you think shalwar kameez is appropriate clothing right? Hindus wear shalwar kameez and they are polytheist. So wouldn't that make you look both like a non-muslim and a polytheist? I certainly think Hindu before Muslim when I see an Indian woman in a Shalwar Kameez.
Seriously though, I think it actually means to not go so far off base that no one would even believe you are Muslim if they looked at you. If you are running around in a mini skirt and tube top with your hair down and lots of makeup then you say to someone "I'm a Muslim" no one will believe you. You don't look like one and the behavior contradicts every hijab ruling of the Qur'an. You look like an "unbeliever". You might not be an unbeliever, but you look like one because you are ignoring every rule laid out for you by the Qur'an. You look like you don't believe in the rulings God gave you. I really think this is what that means. Not "no Western clothing". Because even if you don't wear a scarf but follow all the other modesty requirements you can still look like a believer. Some will obviously disagree (Please no more hadiths or Ayahs Ive seen them all), but if you take hijab into your heart and dress modestly you can still be more a believer than one who walks the walk but does not talk the talk so to speak. Looking like you follow hijab is not enough: you have to follow it with your heart too.
What do you all think?