Churches, college ministries, small group communities, etc are like stars.
Within a healthy (stable) star the dominant forces are the gravitational force (stars are really big) and the expansive force (stars are really big nuclear fusion reactions). Normally a star's stability comes from a balancing of the gravitational pull inward and the expansive push outward.
Disturb this equilibrium and we get things like supernovae and black holes. Without gravity a star's explosive nature would rip it apart. Without the expansive force the star undergoes gravitational collapse, then supernovas, and creates a black hole.
Christian communities are like stars. Discipleship is like gravity and outreach is the expansive force within a given community. For a group to excel we need a balance of both.
With a "no discipleship all outreach" mentality a community will send people out, but will have nothing to draw them back in. Eventually the group will come unglued and drift apart. It is hard to stay committed to, let alone invite others into, a group that has nothing to offer you. It's a used car salesman sort of situation; things seemed to interesting until you signed up.
A group without outreach will become too inward focused and the group will collapse in on itself. As cliques form and the group breaks down many of the former members will leave like the supernova blast before the final celestial death. A black hole is so named because even light cannot escape from its gravity. It is invisible to anyone on the outside and dead to the world. You cannot be the light of the world if no one else can see you.
Instead of either scenario discipleship and outreach should reinforce and spur each other on. As we mature our desire to reach out should only increase, and outreach should drive discipleship.
In my experience our tendency is the inward discipleship of those already within the group. This is fine, it simply means that more attention must actively be given to outreach and evangelism. If our default is inward may we work all the more to push outward for others, ourselves, and the health of the group.
And so may we be the "light of the world" that "the people who have walked in darkness" may see a great light. Christ has come into the world, let us walk forward in that truth.
