Ed Stetzer has said it would be like telling people to feed the poor and if necessary use food. At a minimum, verbally sharing the Gospel is essential to effective, biblically-faithful evangelism. If we call what do sharing the Gospel (or evangelism), then it must include a verbal proclamation.
Good works like feeding the poor, engaging in social justice, and "living out the Gospel with our lives" are corollaries to sharing the Gospel, but they are not equal to it. These realities flow from the Gospel and should mark the lives of Christians who are seeking to be faithful to the Gospel. But we must not confuse the two.
In their book Total Church, authors Tim Chester and Steve Timmis pick up on this by saying:
There is a tendency in some quarters today to promote a kind of evangelism without proclamation. Acts of service are done or people are invited to experience Christian worship. But without words of explanation these are like signposts pointing nowhere, or worse still, signposts pointing to our good works. The Gospel is good news- a message to be proclaimed, a truth to be taught, a word to be spoken, and a story to be told (p. 54).
UPDATE: For more information on the St. Francis quote and his life, check out this article from Mark Galli, who wrote a biography on the life of St. Francis. He writes:
I've heard the quote once too often. It's time to set the record straight—about the quote, and about the gospel.Francis of Assisi is said to have said, "Preach the gospel at all times; when necessary, use words."This saying is carted out whenever someone wants to suggest that Christians talk about the gospel too much, and live the gospel too little. Fair enough—that can be a problem. Much of the rhetorical power of the quotation comes from the assumption that Francis not only said it but lived it.The problem is that he did not say it. Nor did he live it. And those two contra-facts tell us something about the spirit of our age.