Would President George Washington be considered an Atheist today? president Thomas Jefferson indicated George Washington didn't believe in that system, and if you asked him the confirm that he was a Christian he would dodge the directly answering that question unlike politicians today.
https://en.m.wikipedia.org/wiki/Religious_views_of_George_Washington#Eyewitness_accounts
Washington himself didn't take communion at church and said he had never done so.
http://infidels.org/library/historical/john_remsburg/six_historic_americans/chapter_3.html
>The Rev. Dr. Wilson, who was almost a contemporary of our earlier statesmen and presidents, and who thoroughly investigated the subject of their religious beliefs, in his sermon already mentioned affirmed that the founders of our nation were nearly all Infidels, and that of the presidents who had thus far been elected – George Washington, John Adams, Thomas Jefferson, James Madison, James Monroe, John Quincy Adams, and Andrew Jackson – not one had professed a belief in Christianity.