We must never take Christ's work for granted. The gospel is not merely something we take to unbelievers; it is the Word that created and continues to sustain the whole church in its earthly pilgrimage. In addition, we must never confuse Christ's work with our own. There is a lot of loose talk these days about our "living the gospel" or even "being the gospel," as if our lives were the Good News. We even hear it said that the church is an extension of Christ's incarnation and redeeming work, as if Jesus came to provide the moral example or template and we are called to complete his work. But there is one Savior and one head of the church. To him alone all authority is given in heaven and on earth. There is only one incarnation of God in history, and he finished the work of fulfilling all righteousness, bearing the curse, and triumphing over sin and death.
Sometimes I think one of the biggest problems of evangelicalism in our culture is our own emphasis on individuality that leads us to all kinds of creative ways of expressing what we think the Bible teaches. The problem with this is, we are fallen creatures and what we think the Bible teaches is more often than not flawed. If we ignore the faithful witness of church history (and who even cares about church history anymore...we can't even respect a hymn if it was written more than sixty days ago!), we are not only prone, but defaulted, to err in our creativity.
We, as witnesses to Christ's kingdom, are not called to be creative, but faithful. We absolutely cannot be faithful unless we are saturated in the Word (scripture) and diligent in the study of our history of thought. Those who ignore their theological history are doomed to (heretically) repeat it.