David Fitch has some very interesting thoughts on this HERE. Perhaps it's more interesting to me because I was at the learning commons he is referring to, and I also know Chris Hunt (who is good friends with my son, and we all had lunch together that day). But I have heard this as an issue on many, many occasions. This is the first time I've seen it addressed in any way other than, "We tried to invite others." I think David makes some good points, along with some really good comments by others that follow.
I also think Chris's post on Thoughts For White Christians is a worthwhile read, maybe from a totally different perspective. Both links are excellent, and if you're interested in such things, I highly recommend them.
Peace out; and in.