One of the best indicators of whether-or-not a church is healthy is how much they’re reaching people who aren’t already in the congregation. The more outward-looking, the more likely it is to be healthy. The more insular, the less healthy.
But, while outreach is a good indicator of health, it can’t stand alone.
In addition to reaching new people, a healthy church also pays attention to nurturing, discipling and challenging its current members into a deeper walk with Jesus. Doing one at the expense of the other creates imbalance and ill-health.