My suspicion was confirmed in a different thread started in the Baptist Forum.
A poster wrote, "It seems that about 2/3 of members are in-active! ("15.7 million members and 5.8 million Sunday worshipers" reported)."
Using that kind of data we could easily deduced that many posters on CF do not worship on Sunday.
Yours in the Lord,
jm
As the poster who made this comment/observation, I was very surprised to see the official membership being 3x Sunday attendance.
There are many valid reasons for people not attending every Sunday: illness, house bound, working (in the UK many more people have to work evenings and weekends than a few decades ago), away for the weekend (in my town most people have moved here for work, so go away at weekends to visit family), holiday (in the UK we have more holiday than 50 years ago, so will be missing on more Sundays), business travel. Then there are reasons due to commitment: there are many more activities that take place on Sundays that compete with church attendance (sport, shopping, recovering from a stressful week, etc).
However, I would be very surprised if this could explain membership being 3 x Sunday attendance. It could be that 2/3 of members never attend. Or that members on average only attend 1 in 3 Sundays. Most likely, somewhere in-between. But since I would expect a significant proportion of people in church to be non-members, it makes these figures even worse!
I think JM's survey is missing an important category between 'almost every Sunday' and 'rarely', which is '1-3 times a month'. From memory, stats for England show that most people who attend more than once or twice a year actually attend at least monthly. I wouldn't call this 'rarely'.
I would expect a healthy church to have people who are (not yet) members. I presume the figures for Sunday attendance would include children, who would not be members in a Baptist church (well, not in England). I would also expect there will be folk who are not (yet) very committed and come just occasionally. This is only a problem if these people are still as UN-committed in ten years time!
In my church, typical Sunday attendance is a little higher than our membership (which is fairly common for English Baptist churches). And that is despite a moderate number of regular members being away any given Sunday. I'm away about 1 in 4 Sundays (but will almost always be in a another church when away). We also have a large 'fringe' who come once or twice a month. And yes, this does make it difficult to notice if someone is missing.
However, church attendance in the USA is still much higher than the UK. In England, about 5-7% attend church on a Sunday. If it was not for immigration, particularly from Africa and the West Indies, this would be even lower.