I propose that there are four main "factions" of Atheists. Below is a list with what I would anecdotally ascribe to be their percentage of the total Atheist community.
40% - Secular Christians: Those who are atheists yet still functionally Christian in the sense that they still ascribe almost entirely to standard Christian ethics. Give to the poor, do not judge others, we are all equal, forgiveness in all things, non-violence and turn the other cheek, etc. Talks about income inequality like its the most important thing in the world. Probably voted for Bernie. Left-leaning, viciously opposed to the death penalty or any form of harsh punishment for criminals. Unironically thinks human life has inherent value despite being Atheist.
35% - Modernists: Atheists who are high on the fanciful conceit of techno-futurism. Logical positivists at heart, will probably argue that philosophy and theology are irrelevant and insinuate that the scientific method has a monopoly over human truth and understanding. Commonly transhumanist, endlessly talks about the benefits of technology. Plays Kerbal Space Program and has the hubris to secretly think that it is humanity's destiny to colonize the galaxy. Claims to be Nihilistic but actually isn't.
20% - Anthi-theists: Those who are openly and actively against religion as a concept, usually reserving a special prejudice in their heart for whatever religion was forced upon them during childhood. Ideally seeks the eradication of all religions in the distant future, imagining such concepts having been abandoned due to their "primitiveness".
5% - Renegades: A loose amalgamation of mostly unrelated splinter-groups who are united by being entirely at odds with mainstream Atheists, and possibly even society itself. This is the domain of "true" Nihilists, anti-natalists, anarchists, criminals, socialist darwinists, anti-humanists, and radical environmentalists.
Thoughts? Any others you can think of?