As noted above, implicit atheism as defined by Smith is "the absence of theistic belief without a conscious rejection of it", while explicit atheism is "the absence of theistic belief due to a conscious rejection of it".
Below is a quote are relevant quotes from a science magazine and science /journal:
“Atheism is psychologically impossible because of the way humans think... They point to studies showing, for example, that even people who claim to be committed atheists tacitly hold religious beliefs, such as the existence of an immortal soul.” - Graham Lawton in the ''New Scientist''<ref name="exist">Unruh, Bob (July 19, 2014). [http://www.wnd.com/2014/07/science-writer-atheists-might-not-exist "Scientists: atheists might not exist"]. WorldNetDaily. Retrieved on February 21, 2015.</ref> science magazine. See also: [[Atheism and life after death]] and [[Atheism and death]]