Separation or Isolation?

C.S. Murphy,
I gave the Paul-on-Mars-Hill illustration after your statement:

I was questioning how you converse with people who are outside the faith if this is your standard, whether they are liberal Christians (most of whom we would assume are unsaved as they deny basic aspects of the gospel) or unsaved people who do not claim Christ at all. I really don't want to quibble about the distinction between isolation and isolation evangelism (a term which I had never heard before until I made it up on this thread--or did you make it up? ). Let me put it this way. Clearly the Bible teaches that we, as Christians, are to be in the world but not of it, we are to be friends to sinners as Jesus was, but holy and separate from sinners, as Jesus was, and we are to love the brethren--all of them, even though we must sometimes separate from brethren for various reasons. My question for fundamentalists is: are we doing part of what we should (i.e. not being of the world, being holy and separate from sinners, and separating from brethren) while refusing to do part of what we should (i.e. attempting to live in a way in which we are disengaged from the world around us, not befriending sinners, not loving the brethren) resulting in our being isolationists. I ask this question with humility because I do not know exactly how to balance all of these things in every situation. I also ask this question because, it appears to me (and I may be wrong) that the desire for a separate forum for fundamentalists in which we never have to answer a question from outside of fundamentalism or encounter anyone who might have a different view is indicative of an isolationist mentality.