Actually, if you want to go back to the earliest origin of life on Earth, you are looking at a billion or more years.  This is scientifically defensible.  No legitimate scientist even questions it.  It's not "Darwinism" but paleontology, geology, physics astronomy, etc.   If theology does not comport with fact, then it is indefensible.  Nothing more sad than watching a fundamentalist try to defend the myths of the bible, which renders them absurd and only makes the defender appear deranged.