Put another way, that is one very bright light! Paul says thats the way that Christians are to stand out in a dark world, as stars, as lights, guiding the way. By working out our salvation with fear and trembling, or working out what God has worked in, we do this. We point people to Christ by being sanctified and becoming more like Christ.
He gives several ways to do that, like doing all things without grumbling, but the last way he tells us to do it is to hold forth the word of life. By holding out God's word, it is not only a light to us, but to others as well.
Phl 2:12-16 12 So then, my beloved, just as you have always obeyed, not as in my presence only, but now much more in my absence, work out your salvation with fear and trembling; 13 for it is God who is at work in you, both to will and to work for His good pleasure. 14 Do all things without grumbling or disputing; 15 so that you will prove yourselves to be blameless and innocent, children of God above reproach in the midst of a crooked and perverse generation, among whom you appear as lights in the world, 16 holding fast the word of life, so that in the day of Christ I will have reason to glory because I did not run in vain nor toil in vain.
