Well, actually, it is best to be both! (This post originally went with our description of a commitment to reach out through serving and point to unity, not division, with kindness.)
In a real sense, we are all apostles of Christ. Quite simply, an apostle is a messenger, or representative sent with a message. We, as the Church, are called to represent (or "re-present" as in present him again) Him to the world and carry His gospel message.
In the western world, we have understood this point, but usually made the focus of the gospel message about how to reach heaven in the afterlife rather than saying or doing much to impact this life. These don't have to be, and should not be, mutually exclusive points, but to paraphrase one author, we often focus so much on being right and dismiss the responsibility to be good in our world...maybe if we gave more attention to being good, this might help others to see that following Jesus is right. The gospel message is that Jesus is not only right, but also good. And the truth is that one cannot be correct without the other.
I want to throw out a couple comments from one author for your consideration.
"Remember, in a pluralistic world, a religion is valued on the benefits it brings to its nonadherents."
"We must rejoice that God cares for the whole world and set our hearts to join God in caring."