Christian proclamation might make the gospel audible, but Christians living together in local congregations make the gospel visible (see John 13:34-35). The church is the gospel made visible.
Mark DeverAdvice on evangelism needs to be tailored to individual situations. For instance, I know someone who needs to be encouraged to speak less and work more. That would be a better testimony for him because he has certainly let his work colleagues know about Jesus. It's not that I don't want him to witness about Jesus, but I have a lot of sympathy for his employer. He is paying for work to be done.
Mark Dever