Inward and outward looking churches

Is there any legitimate reason for Christians to have a missional focus on those inside the church? Frost and Hirsch in The Shaping of Things to Come describe a teachable moment they experienced which helped resolve this contentious question:

“In a recent conversation with Leonard Sweet, we were stimulated to think about how the church’s stance is always so inward. Len told us about how he will often get Christians who come to his conferences to stand in a large circle around the room. He said that they always stand shoulder-to-shoulder facing inward. When he points this out, they immediately adopt the opposite stance and face outward. But Leonard Sweet reminds them, a totally outward-facing church isn’t being everything a church should be. He then asks them to stand facing each other with one shoulder facing the center of the circle and the other facing out. It might seem like a small shift, but by standing in this less natural position they gain a powerful reminder of the missionary stance. It’s both inward and outward looking.” (2003, pp. 45-46)