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In his article, Professor Friedman analyzes a report by "Church Growth Today" (found here) which names the Top 50 Most Influential Churches in America. An interesting list, Friedman correctly points to some flaws and qualifiers regarding the list.
First, the report only consulted non-Roman Catholic clergy and only included non-Roman Catholic churches on its list. Is it that unreasonable to expect at least one congregation of the largest denomination in the country might make the list? What is "Church Growth Today" afraid of? Yes, Roman Catholic ministry tends to be very different from much Protestant ministry, but that doesn't invalidate an entire denomination.
Second, the report only consulted the pastors of the nation's largest (non-Roman Catholic) congregations. In other words, the report tells us how large church pastors influence one another, but may not say much about how influential these churches are among the majority of Christians in America, who do not worship in these "megachurches".
Finally, Professor Friedman properly asks if this poll is a fair and accurate measure of actual ministry. A rural congregation of 50 might be doing miraculous ministry in its context, and may be producing far more tasty fruit than a large megachurch; this little church may ultimately have far more influence than a megachurch.
Why does it seem that so many Christians in America are obsessed with size?
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Now, that said, many of the churches which made the list are doing wonderful things. There's no denying the influence of Willow Creek and Saddleback. Southeast, Resurrection, Mars Hill, Frazer, and Windsor Village are all doing tremendous things. Some of the churches on the list have serious theological problems. Some present a very watered-down Gospel.
The point is that a tree which produces a great deal of fruit is not necessarily a tree which produces the best quality fruit or the tastiest fruit. Let us not get too preoccupied with contemporary numerology, which emphasizes numbers, at the expense of faithfully harvesting excellent fruit.