This post simply is nonsense, the average lifespan of people back then was around 30 to 40 years,, and Matthew, Luke and John were written much, much later on. Additionallly, there certainly is no extra-biblical evidence whatsoever that Matthew, Mark, Luke and John ever existed.
I've been assiduously avoiding the whole off-topic discussion about the gospels, but I can't let that pass.
The average life expectancy argument falls flat because life expectancy figures, up until very recent times, are heavily skewed by infant and childhood mortality rates. For instance, I seem to remember reading that 3 out of 5 people born in 14th century Europe died before the age of five. The thing about life expectancy is that the longer you live, the better your chances of living even longer. If the average life expectancy is 35, that doesn't mean nobody lives to the age of seventy. For example, one of my direct ancestors attained the age of 94 at a time when the average life expectancy was 38.
It's not at all unreasonable for believers to think that people who knew Jesus were still living 40 years after Jesus' death, which gets you to about the time Mark was written. There are good reasons for thinking that the gospels -- and especially the three other than Mark -- were not written by eyewitnesses, but life expectancy isn't one of them.
On topic: I don't know what someone who approaches The God Delusion with a pre-conceived dislike of Dawkins should expect to get out the book. It's hard for me to say, since I like Dawkins very much, especially because of
The Ancestor's Tale.
When it comes to theism, I think Dawkins' chief shortcoming is that he's genuinely dumbfounded by the religious excesses he comes across. He seems at times to throw his hands up and say, "Can't you see how
insane this is?!" And of course the point is that they can't see it at all. I don't think he can really understand what it is to be so immersed in religious dogma that it all seems quite normal and reasonable.
I think that might be why it's hard for most true believers to connect with Dawkins. His writings are useful and entertaining mostly to people who already agree with him and to those who are already questioning their faith. However, he's performed a tremendous service in giving a lot of atheists the courage to be more open about their atheism, and he helps keep the discussion going. A lot more people are thinking and talking about atheism, religion and ethics because of Dawkins, and I think that's a very good thing.