The Pope says that we bit off more than we could chew.

Within 12 to 18 months, about 40 percent of U.S. borrowers, or 20 million households, will owe more on their mortgages than their homes are worth. The problem will be most severe in California, Nevada, Florida and Arizona, where housing prices soared and reckless lending practices were rampant during the housing boom.

That's almost the same number of American households that are spending 30 percent or more of their income on housing, according to recent U.S. census data. With little cash cushion or home equity, the slightest financial problem can put a family behind on its mortgage and into the realm of foreclosure.