Are you saying that because someone claiming to be a Christian* has misunderstood something important then Christianity is wrong?
No. I'm saying that you have no methodology to be able to state that somebody else's - to you - "misunderstanding" of something in Christianity actually is a misunderstanding, because every time somebody asks you to provide one you bottle it. Goodness only knows we've had enough evidence of this over the months, haven't we?
The exact same applies to your characterisation of something as "important." That may very well be your opinion, but that's all it is because you refuse to provide any means of determining it to be such.
I think it's fairly clear from a biblical, historical and churches doctrine point of view what is orthodox, mainstream Christianity and what isn't.
How philosophy works Shaker is that ideas or notions are put forward into the arena and weighed up.
In theology and religion ideas and notions which aim to be Affective and effective in soliciting whole life commitment are put to people for the weighing up.
This is why some talk bluntly but rightly of Antitheists being evangelical and fundamentalist because they seek antitheist commitment in thinking and practice and in spreading that thinking and practice in wider society.