Basic Error No. 1 Church = Program
Just because lots is going on doesn't mean that anything important is happening. In fact, if leaders get too distracted keeping all the balls in the air, they can miss their visitation -- Jesus slips out, unnoticed, ungreeted, uncared-for amidst all the razzmatazz.
(Now mind you, program is a good thing. Most spiritual error consists of misappropriating the good in a less-than-optimal way.)
Basic Error No. 2 Church = Performance
Lots of people think that the essence of Church or the effectiveness of worship is about the people standing up front. This is wrong. Neither cabaret-style "contemporary" worship with its skits and choruses, nor the flawless execution of intricate ritual by the bells-and-smells crowd is the point. God is the audience, not the congregation; the congregation are the actors, not the leaders up front.
Basic Error No. 3 Church = Commodity
Many churches these days think they are successful because they are good at "putting seats in the seats." But having lots of customers doesn't mean that the product is really good, only that it's scarce or fashionable. Many people value churches which match their priorities, which means those churches are compromised in trying to critique their customers' priorities -- and thus they are handicapped in trying to help them grow spiritually.
Basic Error No. 4 Church = Place
The lonely and the lost don't give a rip about your tracker pipe organ or the date on your cornerstone or who's buried in your cemetery. These are all nice things, but they don't feed the starving soul.
Basic Error No. 5 Church = Experience
I know a lot of folks who think that church is irrelevant next to "being saved" or "baptized in the Spirit" or however they articulate their most important experiences of God. But we did not invent the Faith by our cleverness, we learned it from others. It was passed on to us. Without others' experiences, ours lacks perspective -- and so do all those who think their personal experience is sufficient without wrestling with the Church.
Basic Error No. 6 Church = Cause
Back in the '60s, lots of artists influenced by the Civil Rights movement and other social causes recorded folk hymns, spirituals, etc. But when the issues of the day moved on, their "faith" moved on with it. David Seamands said it best for me: The Church can be co-belligerents with anybody, but we are allies of none. Nobody else has the total viewpoint the Church has on what's wrong (and would be right) for Society. Causes come and go, but Christ is "the same yesterday, today, and forever."