I agree with you that many eighteenth-century Deists might have been atheists had they been familiar with the work of Charles Darwin. However, Darwin’s theory of natural selection only explains that we have a variety of species, including human animals, because they adapted to their environment. Evolution says nothing about how life began. Many Deists would probably still have believed in a Creator who started the process, and then let nature take its course. Later scientific discoveries would probably have turned these Deists into atheists. We now know that our universe did not begin with a Creator, but with a “Big Bang” approximately 13.8 billion years ago. We still don’t know how life began, although abiogenesis is a reasonable hypothesis. This is the natural process by which life has arisen from non-living matter, such as simple organic compounds. It’s interesting that Bible believers refuse to believe this hypothesis about life arising from non-life, though they believe that the first human was made from dirt and the second human from the rib of the first. Did God run out of dirt?