Final answer:
The section indicating that atheists and agnostics are typically not an organized group supports the idea that they are not united around common beliefs, contrasting with religious communities that share specific common traits.
Step-by-step explanation:
The section of the article that best supports the idea that atheists are usually not united around common beliefs is where it states, "While typically not an organized group, atheists and agnostics represent a significant portion of the population." Unlike religious groups that share common characteristics like a belief in the supernatural, moral codes, and rituals, atheists and agnostics are not typically organized and do not necessarily subscribe to a common set of beliefs or practices. This lack of a unifying doctrine or organization suggests that atheists are not united around a set of common beliefs, as opposed to what is typically found in religious communities.