My evangelical parents, when I told them what I'd learned about Quakerism, were horrified and considered it the blackest of heresies - specifically, the idea that everyone has a bit of God in them (I'm a little fuzzy on the actual name of this idea - something about light, if I remember correctly) My mother started yelling that we are ALL born evil and utterly without God and that to teach otherwise is to lead people to hell...
Quakers used to get branded and run out of town on rails a few hundred years ago, so I think the idea that they sre heretical non-Christians isn't new.