I'm looking for a word that could be used to describe a group of people who believe the same thing.
The members of the blog site worked hard to win others over to their political views, unaware that their follower base was _______.
In this case, their followers already share their views, which, unbeknownst to them, makes their arguments moot.
"Like-minded" is close, but not quite right (perhaps because it lacks the connotation of ignorance), and I would prefer a single concise word.