I have written you in my letter not to associate with sexually immoral people – not at all meaning the people of this world who are immoral, or the greedy and swindlers, or idolaters. In that case you would have to leave this world. But now I am writing you that you must not associate with anyone who calls himself a brother but is sexually immoral or greedy, an idolater or a slanderer, a drunkard or a swindler. With such a man do not even eat.
As Christians, we are to be in the world, but not of it. It is very clear in this passage. We will find ourselves associating with those in the world who are greedy, immoral and swindlers. As Christ’s ambassadors, we do not choose to go the way of the world even as we find ourselves working among them. However, if someone says he is a Christian, but continues in sin, we are not to associate (have close association) with them. In fact our instructions are even more severe: we are not to even eat with them.