it's not really a divide among leftists, since new atheists represent a very small part of left (usually left, but it is not a political group per say so there may be some right wing new atheists too). It is specifically a "war" between the *Regressive* Left (Glenn Greenwald, Cenk Uygur, Reza Aslan, Noam Chomsky) and the New Atheists (Sam Harris, Richard Dawkins, Bill Maher, Christopher Hitchens)
Here is a few link if you are interested by the subject:
New Atheists Vs Progressives | Proposing A Ceasefire
https://www.youtube.com/watch?v=As67_rhvTVYSam Harris and Cenk Uygur Clear the Air on Religious Violence and Islam
https://www.youtube.com/watch?v=WVl3BJoEoAUChomsky on Hitchens, Harris and Skinner
https://www.youtube.com/watch?v=zt9QCAUPPeYMaajid Nawaz on Sam Harris and the Regressive Left
https://www.youtube.com/watch?v=X6Vjn3d70UQ
Edited 2/3/2016 20:15:13