The mainline denominations do seem to be weak in the sense of being unable to generate and maintain high levels of commitment among a substantial portion of their adherents. Although we are skeptical of Kelley’s argument about the relation between strictness and church growth, he is right that weak churches are in a precarious position as organizations because further weakening may diminish their members’ commitments to the point of noninvolvement.
via Mainline Churches: The Real Reason for Decline.
Benton Johnson, Dean R. Hoge, and Donald A Luidens look at the mainline decline, and come to the conclusion that people don’t show up because it does not matter.