Read this story from the Christian Science Monitor. Interesting story and issue - the Pew Forum on Relgion&Public Life released its "Faith in Flux" survey today, and there's a whole lot of moving and shaking going on.1
Some big take-away messages: Catholics tend to leave their church because of doctrine, while Protestants tend to leave because of life changes such as marriage. About two-thirds of people born and raised Catholic stay with the faith, while 80 percent of Protestants remain so (although only 52 percent stay with the denomination of their childhood).
But you can't get far into the story without losing the big picture - there are more in there than in a TPS report. Every J-school student learns at some point that numbers, used badly or not at all, can muck up a story. Perhaps this Monitor article could have worked better as a charticle.
1 I do like the irony of the Pew forum on religion. Countless generations of children entertained themselves in church with jokes about pew. Or at least I did. For word nerds like Patrick: the word 'pew' probably comes from the old French puie, or balcony. Also, the sample limitations "prevented the inclusion of smaller groups (such as converts to Catholicism)," so no word on whether Grandma's prayers to the Sweet Baby Jesus have worked.