 At the “Reason Rally” in Washington, secular, atheistic people gathered 
in support of “reason” over [mere] “faith” of religious people. Not so 
hidden in the background was the 
widely-held cultural mindset that science uses reason and uniquely gives
 us knowledge of truth (the facts). But religion gives us just personal 
opinions and preferences, not knowledge. This bifurcation often is 
called the “fact-value split.”
At the “Reason Rally” in Washington, secular, atheistic people gathered 
in support of “reason” over [mere] “faith” of religious people. Not so 
hidden in the background was the 
widely-held cultural mindset that science uses reason and uniquely gives
 us knowledge of truth (the facts). But religion gives us just personal 
opinions and preferences, not knowledge. This bifurcation often is 
called the “fact-value split.”This science is naturalistic; only what is scientifically knowable (i.e., by the five senses) is real. In principle, such things as God, souls, and mental states (i.e., non-physical things like thoughts, beliefs, and experiences) cannot be known to be real. Or, simplifying, they don’t exist. Yet, we can test natural, physical stuff scientifically, so that is what is believed to be real. That view of reality is the philosophy undergirding atheistic evolution by natural selection (NS) – naturalism. There’s only the physical universe, without anything non-physical.
 

