Population growth is a measure of a cultures economic success as well as its faith in the future. I would argue that with the 40+ year campaign of post modernism and its constant deconstruction of any and all institutions that the public (those that listen to them) start to believe that all life is futile. If futility is your starting point, chances are pretty good that you won’t be having a large family. With our country, we have been using illegal immigration to offset the drop in fertility. This, as the Europeans know, is a problem. Funny thing is the illegal alien produces offspring at double the rate of native born Americans. Guess they have a positive attitude towards the future. From an objective point of view, who do you think is happier, the post modern intellectual, or the illegal alien who cherishes the Catholic Church? You can choose to see life as futile or fanstastic (half empty/half full) the only difference seemingly is one is happy, the other not.
I'd definitely put my money on the illegal alien. Of course, that does not mean that the solution is to encourage illegal immigration. ;-) And I believe it is a bit of a misconception that all or even most of the illegals coming across the borders 'cherish the Catholic church.' Many are only nominally Catholic (think European here.) I believe the main motivation is to participate in the opportunity the American Dream holds for people. They are just as likely to become caught up in the materialist side of the American Dream as native born citizens. Unless I am mistaken, first and second-generation immigrants tend to have higher birth rates than native Americans, while by the third and fourth-generations the rates decline to the norm.