The trends away from religious identification and devotion are worldwide and broad, though.
According to the U.S. Statistical Abstract, 86 percent of American adults identified as Christians in 1990 but just 76 percent in 2008. Research from the Center for Applied Research in the Apostolate shows that 32 percent of Americans who identify themselves as Catholic rarely or never go to Mass.
Australian census data show that in 1991, 27.3 percent of the country identified as Catholic and 74 percent as Christian of some sort. Those percentages have declined every five years since, to 25.3 percent and 61.1 percent respectively in 2011. A 2009 survey for the country’s bishops conference noted that of Australians who reported being raised Catholic, one-quarter said they now had no religion and more than 40 percent said they never attended Mass.
World Youth Day host nation Brazil, a historically Catholic country unlike the U.S. and Australia, is not immune. The share of its population that calls itself Catholic declined from 92 percent in 1970 to 65 percent in 2010.
The Sydney Diocese and surrounding dioceses “did claim a noticeable increase in attendance after World Youth Day, but it’s very hard to quantify it or determine how long it lasted or whether it was due” to the gathering, Father Mason said in an email. “The general trend in [Catholic] attendance is strongly downward, especially among youth, and had been going on for a long time before World Youth Day.”
• This article is based in part on wire service reports.