Two levels of citizenship are implied: they were citizens of heaven living as lights in the darkness, and without compromising their testimony, they should also be good citizens of their city. Our citizenship is in heaven, and we are an outpost of believers in a fallen world, but while we are in this world, we need to engage our communities in such a way that we make Christ appealing to the lost. Just like millions of people want to come to America, our joy, peace, and love should make others want to become followers of Christ.
In the text we see a stark contrast between two men—one was courageous and the other a coward. One stood up for what was right, but the other capitulated to his guilt and fear of public opinion and did something terribly wrong. One thing we know for sure is that it takes courage to be Christian in a world that increasingly embraces all manner of evil. It is a world wrestling with its guilt by blaming others and pointing fingers rather than looking in the mirror and accepting personal responsibility for the choices they’ve made or the consequences of those choices.