That's a common misconception that perhaps Ehrmann deliberately pushes. He himself says that no core doctrines of Christianity were changed by the variants and that the books we have today are essentially the same as the originals, though not word for word identical.[1]
Few who cast unwarranted doubt upon the New Testament realize how extremely sceptical they would have to be about every other piece of ancient writing, because none of them even comes close to the new testament in terms of:
1) number of copies
2) being written close to the time of the actual events
I know it is not "in fashion" today but the description of Megan's illness, resistant to antipsychotics as it was, "arguing with Jesus" calling her self "evil," etc, pretty much matches up with the traditional accounts of demonic possession. Suppose there are anti-human intelligences in another plain of reality and that they can metaphysically sense a "vacant" vessel, like somebody in deep meditation. Such individuals would be at elevated risk of demonic possession.
Few who cast unwarranted doubt upon the New Testament realize how extremely sceptical they would have to be about every other piece of ancient writing, because none of them even comes close to the new testament in terms of: 1) number of copies 2) being written close to the time of the actual events
[1] https://crossexamined.org/is-the-new-testament-reliable-erhm...