There is only one U.S. religious group, propelled in part by an enthusiastic group of young followers, that is expected to grow to 100 million adherents by the middle of the century. Yet to hear some critics focus on generational shfts showing declining Mass attendance and doctrinal commitment among white Catholics, one might think the Catholic Church is slowly sinking in the U.S. religious landscape. So which is it for the nation’s largest religious group, growth or decline? The answer is some of both, researchers say.