sectarianism in atheism

[robvalue]

No. It’s a matter of definition, mostly. Some people use it to mean lacking belief (not being convinced yet) that gods exists; some people prefer belief in the non-existence of gods. The second is a subgroup of the first, so it splits atheists up in that regard as to how strong their position is, but I’d hardly call those sects.

Of course atheists will have their own further beliefs about everything, which will subdivide them into whatever groups you want to talk about, but those are nothing to do with atheism itself.