Catholic Population Declined?
The data collected for the study also show the total number of Catholic adherents—the number of baptized Catholic individuals recognized by each parish and mission in the United States—at 58.9 million, three times that of the second-largest religious body, the Southern Baptist Convention.
Grammich noted that the total number of Catholics in the United States reported in the 2010 study indicates, on the surface, a decrease of approximately 5 percent from the 2000 total of 62 million. But, because the methodology used to collect the data changed for the 2010 study, he says it’s difficult to draw absolute conclusions when comparing the Catholic statistics in the two studies.
(Read more about the definitions used in the study and the accuracy of the statistics.)