I don't think it's mind boggling. If one were to read the GT on its own, which includes their so-called old testament, I don't think any contradictions or fabrications would be evident. Within their own book, everything is consistent. Even if it's not internally consistent on the plain reading, then I'm sure their authorities provide interpretations to make it work. Besides most people don't belong to a religion based on reading that religion's holy book. The majority of people start with the religion of their parents. High level logical analysis, reading of other religion's book, and comparative study of those different books on a verse-to-verse basis is not done by the vast majority of people. For example, I've never read the GT. I rely on explanations from knowledgeable Jews that have.