The Association of Religion Data Archives released its 2010 U.S. Religion Census yesterday.

Its summary reports that mainline Protestant churches in the U.S. lost an average of 12.8 percent of adherents in the first decade of the 21st century. Catholics lost 5 percent of their active members in the ten-year period.

Here is how some of the largest religious bodies in the U.S. fared from 2000 to 2010:

Muslims:   +66.6%
Church of JC of Latter Day Saints:   +45.5%
7th Day Adventists:   +29.5%
SBC Baptist:   +0.1%
UMC Methodist:   -4%
Catholics:   -5%
LCMS Lutherans: -9.9%
Episcopalians:   -15.7%
ELCA Lutherans:   -18.2%
PCUSA Presbyterians:   -22%
United Church of Christ:   -24.4%

The entire U.S. population increased by 9.7% from 2000 to 2010 according to the U.S. census, so a religious body would need to have grown by 9.7% just to maintain its proportion of the population.

For Catholics and mainline Protestants, these are some hefty drops. And of course the question for Catholics is how much our figures are helped by immigration of Catholics. What would our figures be without immigration?

The percentage of Catholics in the US population as a whole has dropped significantly in the last decade. This compares with small growth in earlier decades:

2010:  19%
2000:  22%
1990:  21.5%
1980:  21%

The report shows growing religious diversity in the U.S.:

This is fun: the online database lets you look up the info for any county or state. Stearns County in central Minnesota, for example, the home of Saint John’s Abbey, was long a bastion of German Catholicism. But that’s changing rapidly. Here are the percentages of Catholics in Stearns County in 1980, 1990, 2000, and 2010:

 58.9 > 58.5 > 50 > 41.5

A partial explanation for the decline, I suspect, is that the U.S. population as a whole is moving around and mixing itself together, which means the odds are that the Catholic percentage will decline in its former regions of domination, but increase where it was previously a tiny minority, such as in some of the southern states.

I grew up in southern Minnesota, down in Lutheran (mostly Scandinavian) territory. Here are the percentages of Catholics in Renville County in 1980, 1990, 2000, and 2010:

27.2 > 29.8 > 27 > 24.5

The Lutheran proportion of the total population is also are declining. Here are the figures for ELCA and WELS Lutherans respectively:

 35.5 and 12 > 34.9 and 12 > 33.4 and 10.2 > 31.7 and 8.8

In 2010, Catholics are 21.7% of the Minnesota population, and all the Lutherans put together (ELCA, LCMS, WELS, lots of miscellaneous little Lutheran bodies) are 22.2% of the state. In 2000, Catholics were 25.6%, all the Lutherans put together were 25%. So our share of the population is declining somewhat more than is the Lutherans’.

I bet you Amis out there will be looking up various states and counties. Enjoy.