As I think about what church is, I like what one of my former professors at Asbury, Howard Snyder, has to say in his well known book, The Problem of Wineskins:
The gospel says, "Go," but our church buildings say, "Stay."
The gospel says, "Seek the lost," but our churches say, "Let the lost seek the church."
Or, as Neil Cole puts it:
"If you want to win the world to Christ, you are going to have to sit in the smoking section."
This is a reminder that church isn't just a once a week thing, but should make up the essence of our everyday lives which are spent "in the world." And it's in this world, in the smoking section, that we find the lost. Don't leave the world and try to shelter yourself from it. Instead, engage the world and by doing so, the power of the gospel through your witness will shine for all to see and the lost will be found.