I’ve been thinking about hope a lot lately. Probably, this is a result of studying the writings of John. The Gospel of John talks about the darkness of this world and the hope that is found in Jesus Christ. Recently, our church held candlelight services on Christmas Eve. It can be a powerful experience to watch one light multiply into hundreds or thousands to fill up a dark room. 
The basic thought is that Christ is the first light, and Christians are the lights that follow him. Ultimately, Christ and his followers light up the dark world. I’m not sure Christians can ever really light up a dark world, though. I think it more likely we can only point out just how dark it really is without light (as though we really need to point that out). We can tell people that there is light that illuminates the dark. We can direct people to the source of that light. We can tell people that there exists a world where there is no dark and that they can have a place in that world of light. So when those candles start lighting up the dark church sanctuary, what I see is symbolic hope. We can have our darkened souls awakened to the awareness of light, and the hope of that future world where we can live in the light.