Children under age 2 can reason abstractly, researchers say. Jandrie Lombard/iStock hide caption

itoggle caption Jandrie Lombard/iStock

"I felt so lucky to be Catholic and I loved the Catholic school and I loved the nuns ... then when it came to the belief part of it I was always a little bit skeptical" — Julia Sweeney James Duncan Davidson/TED hide caption

itoggle caption James Duncan Davidson/TED

Rev. Billy Graham speaking at a TED conference in 1998. Courtesy of TED hide caption

itoggle caption Courtesy of TED