While the Bible specifically speaks of our "brother", I think it really applies to us whenever and whereever we are.  As we've discussed on ITM before, modesty is first and foremost a heart issue which means it shouldn't change based on who we are around (Christian or non-Christian); it's hypocritical.   When we are around Christian men, I think the burden is shared–for us, to do our best at dressing and acting modestly, and for our brothers to direct their eyes and thoughts in a holy direction. When we are around non-Christians, we have the same obligation.  However…the men may or may not behave morally. At that point, there is only so much we can do to keep their mind pure but dressing/acting modestly still protects us…much like standing under an umbrella in the rain. 

Does that answer the question, or not really?

I agree with Foy. We do set an example to non-Christians and they do watch us. I often wonder what they think when they see Christians dressed exactly like the world. I have been thinking alot about this the past few days and we are told to be in the world but not of it. I have started to aproach modesty with the mindset that I aproach life with. I want others to see Jesus Christ shining through me whether they have known me for six years or whether they have just met me. I have realized that if I am dressed immodestly and causing brothers in the LOrd to stumble then that is not bringing honor and glory to Jesus. If I am causing others to stumble before I even have the chance to talk to them…something needs to change. 

I hope that made some sort of sense