Theo is an untrustworthy narrator. Because the book was written, not only from his point of view, but also from someone who is initially seemingly innocent, we are supposed to feel that we can trust him. But as the book continued on, we see how that was never the case.
The novel begins with a preface written by the translator describing how he discovered the tale, didn't really believe it, but then came to see that it must be true. We are encouraged to "suspend our doubts and peer deeper into the story, seeking authentic truths hidden beneath the surface preposterous" (Fletcher 189).