Article by Phil Zuckerman
http://www.secularhumanism.org/index.php?section=library&page=pzuckerman_26_5
From the last paragraph:
Belief in God may provide comfort
to the individual believer, but, at the societal level, its results
do not compare at all favorably with that of the more secular
societies. When seeking a more civil, just, safe, humane, and
healthy society, one is more likely to find it among those nations
ranking low in religious faith-contrary to the preaching of
religious folks.
Edit: Removed the allegation of 'successful' states to address the
lack of definition of success. The criteria of evaluation is
discussed in the article.