There are still some people who are persuaded by scriptural evidence to believe in God. A common argument, attributed to C.S. Lewis (who should have known better), states that, since Jesus claimed to be the Son of God, he must have been either right or else insane or a liar: 'Mad, Bad or God'. Or, with artless alliteration, 'Lunatic, Liar or Lord'. The historical evidence that Jesus claimed any sort of divine status is minimal. But even if that evidence were good, the trilemma on offer would be ludicrously inadequate. A fourth possibility, almost too obvious to need mentioning, is that Jesus was honestly mistaken. Plenty of people are. - Richard
Dawkins
Waking up one morning and thinking it is Thursday when it is actually only Wednesday, or thinking that your shoes are in your closet when you actually left them in the living room are examples of being honestly mistaken. Believing you are the Son of God as the basis of your life experience, your teaching and your death is a belief far beyond something that could be reasonably categorized as an honest mistake.
Going through the book, it is not that Dawkins never makes a good point or a reasonable argument, but strewn along the paths are so many arguments like this one that, to me, it significantly mitigates the credibility of the book over all. Another aspect that I found frustrating is that at one point when a scientist makes a statement supportive of religion, Dawkins states that he surely must not have meant what he said and that he was under powerful social pressure to be polite to those of faith. So, if anyone says something that is different from you, they obviously didn't mean it? I also find it interesting that he heaps tremendous praise on all of those atheists who were brave enough to stand up for their beliefs in an environment that is predominantly religious, but he considers the praises of those who admire devout Christians who are also distinguished scientists (in an environment that is predominantly atheistic or agnostic) as an act of desperation.