In the past decade or so it has become somewhat common for various social science researchers and even some amateur individuals and groups to construct categories for non-believers. Personally, I think that this is a potentially helpful exercise. One of the more recent studies to take this approach has been reported on in a handful of media sources. The HuffPo piece helps reveals some of the downsides to attempts at categorizing non-believers. "Atheist Study Reveals That Non-Believers Are Just As Varied As People Of Faith" is laced with, though subtle, various myths and stereotypes.
The whole tone of the piece seems to be one of surprise. It does not seem to have previously occurred to the author, Yasmine Hafiz, that non-believers are a very diverse collection of individuals. The piece also treats "atheist", "agnostic", and "non-believer" as if they are synonyms. Given that the whole piece is on separating non-believers into categories this jumbling of terms is a tad bit ironic. Hafiz also seems surprised that not all atheists are anti-religious. She certainly does not seem capable of analyzing why some are anti-religious and to what degree they are anti-religious.*
The piece, in various places, also shows a high level of disconnect. It is as if she thinks atheist are some sort of exotic species that just appeared out of nowhere. Hafiz is apparently unaware that atheists are part of the surrounding culture. It is not surprising that some choose to participate in religious services/practices despite a lack of belief. The "Ritual Atheist/Agnostic group" really isn't that mysterious. As social animals we are prone to the same drives towards acceptance and conformity as any other group of people.
Hopefully, the more the various non-bleievers are studied and scrutinized the less alien we will seem to others. For that purpose broad categories are fine. However, it is misleading. We are not a "religion" or an "ism" of any type. Lack of religious belief is not in and of itself a belief system. Ultimately there are as many "types" of non-believers as there are non-believers.There is only one thing that unites the "none" and even that is debatable and in many ways an amorphous topic. We lack a religious system of belief.
*I am anti-religious. However, I am not opposed to religion based on some type of knee-jerk reaction. I also don't particularly want to be anti-religious. The level of my animosity toward religion does ebb and flow depending on how much influence religion exerts on public policy. If theists kept their faith out of public policy and therefore out of my life I wouldn't give a shit about religion at all. I'd have no reason to oppose it or constantly criticize it.