not the same comparison, you should compare one religion’s body count to communism since communism is just one political ideology. the more accurate comparison should be religion’s body count vs political ideology body count (democracy, communism, socialism, libertarianism etc).
Better or worse than the 200+ million killed by religion? https://www.reddit.com/r/atheism/comments/33tofh/how_many_people_have_been_killed_in_the_name_of/
Discussion
Communism isn’t just one political ideology, but many contradictory and incompatible ideologies under a label that sometimes people we call communist use or reject.