The perceived importance of religion (or religiosity) declines predictably with development (however measured) allowing one to predict how long it will take for religion to become unimportant for the majority of the global population. It will take approximately a quarter-century. This boils down to about a 1 percent decline of religiosity each year.
MORE: http://www.psychologytoday.com/blog/the-human-beast/201305/can-atheism-really-replace-religion?utm_source=feedly
See also...
Most Americans Say Religion Is Losing Influence in U.S.
http://www.gallup.com/poll/162803/americans-say-religion-losing-influence.aspx
Facing Adversity, Some Find Solace in Science
http://www.psmag.com/blogs/news-blog/stressful-times-turn-to-science-58781/
