A minor note: the phrase "Congregational membership continues its decline, but our congregations’ members seem to be increasing in frequency of attendance ...." might seem to be true by just quickly looking at the numbers. But, "average attendance" includes everyone who is attending services and not just the members. "Average attendance" would include guests and long-time attendees who aren't on the membership roles." It would be more "correct" to say "Congregational membership continues its decline, but the average attendance at our congregations seems to be increasing."

Without measuring the number of non-member attendees, we don't know if the attendance is increasing due to the members or if it's due to the non-members.