That is not what I'm saying...
I guess we'll have to disagree, because I think we can take the, for lack of a better term, accepted thoughts of a group and also identify outliers. I'm not trying to act in the spirit of no true scotsman, but I think that a thought needs to have some significance or impact for it to be considered part of a group ideology.
For instance, John Shelby Spong, calling himself Christian, has claimed we need to abandon theism and a literal understanding of Christ's divinity, or the Westboro Baptist Church which claims that God hates homosexuals. Both are claims of avowed Christians, neither of which should be considered part of Christian understanding, because they do not reflect, in any meaningful manner, the thoughts of Christians in any meaningful number.