People aren’t just rationally ignorant about politics and economics; they also seem to be rationally ignorant about religion.  The latest Pew Forum on Religion and Public Life poll weighed, measured, and found wanting the religious knowledge of over 3000 adult Americans:

More than four-in-ten Catholics in the United States (45%) do not
know that their church teaches that the bread and wine used in
Communion do not merely symbolize but actually become the body and
blood of Christ. About half of Protestants (53%) cannot correctly
identify Martin Luther as the person whose writings and actions
inspired the Protestant Reformation, which made their religion a
separate branch of Christianity. Roughly four-in-ten Jews (43%) do not
recognize that Maimonides, one of the most venerated rabbis in history,
was Jewish.

In addition, fewer than half of Americans (47%)
know that the Dalai Lama is Buddhist. Fewer than four-in-ten (38%)
correctly associate Vishnu and Shiva with Hinduism. And only about a
quarter of all Americans (27%) correctly answer that most people in
Indonesia – the country with the world’s largest Muslim population – are Muslims.

Fun fact: Atheists and agnostics are Pew’s two highest-scoring groups!  This result admittedly fails to adjust for education, but it’s striking nonetheless.

Now consider: If people sincerely believed that their eternal fates hinged on their knowledge of religion, their ignorance wouldn’t be rational.  If you could save your soul with 40 hours of your time, you’d be mad to watch t.v. instead.  Unfortunately for religious believers, this leaves them with two unpalatable options:

1. Option #1: Deep-down, most religious believers believe that death is the end.  (This is consistent with the fact that even the pious mourn their loved ones at funerals, instead of celebrating the good fortune of the deceased).  Even if this covert atheism is mistaken, the idea that most of the people in church aren’t true believers seems threatening.

2. Option #2: Most religious believers are so stupid and/or impulsive that they’ll knowingly give up eternal bliss for trivial mortal pleasures.  But why then do so many believers show intelligence and self-control in other areas of life?