There is, in fact, a reason why I called my blog 'Flesh or Spirit'. I don't know if you have ever read the Circle Trilogy by Ted Dekker, but it is really good. Throughout the three books, it talks about the difference between those of the flesh and those of the spirit. The people who live in sin look physically different in the trilogy. Their skin peels and is pale white, and it gives off a foul odor. Those of Christ's spirit are smooth skinned and tan and don't smell.
In our world things aren't always that clear cut. You might not be able to tell if a person is a Christian or not. Unfortunately it is not always obvious. So we have to learn, as Christians, to live as people of God's and spirit and not be of the world. And as the main character realizes by Dekker's third book, we are called not just to step out of the world, but to pull the unbelievers out as well. We must be willing to embrace them even in unbelief and love them as God's children.
So what are you? Are from the Horde and of Flesh? Or are you a one with God's Spirit?