Ehrman starts out by saying that he can sympathize with those Christians who say that despite its various contradictions, forgeries and differing opinions, the Bible is still an inspired, divine book. In fact, this was Ehrman's own belief for many years: he became a liberal Christian before losing his faith entirely due to the problem of evil. He thinks that acknowledging the Bible's problems can lead to "a more intelligent and thoughtful faith."
It's certainly true that such a view would be more in line with reality than the demonstrably false view that the Bible is unified and error-free. But I think that the liberal Christian merely trades one kind of absurdity for another. Such people are forced to believe that an all-knowing, all-powerful überbeing who wants desperately for us to know and understand him... is a flat-out terrible communicator. If the Christian God exists, there is no question that he could have done a better job of getting his message across than he has with the Bible. Even if he didn't want to warp the free will of the biblical writers and translators by guiding their hands, he could simply have changed the copies after they were made. Is this is too demanding? When we're talking about a God who can perform any task effortlessly, I think not.
Ehrman also suggests that the Bible may still be useful to Christians as something they can apply to their daily lives (while taking into account its historical context). He says that for a long time the claims of Christianity "resonated with me extremely well." In particular, he admired the message behind Jesus' selfless sacrifice and found encouragement in the eventual triumph of life over death.
There are two problems with this. One of these Ehrman acknowledges himself: much of the Christian message is reprehensible, from the mass killings of innocents in the Old Testament, to the denigration of women and homosexuals, to the idea of eternal punishment for the "crime" of unbelief. If liberal Christians are going to live by the Bible, they had better be very careful about which parts they choose. The second problem is that Ehrman never acknowledges that other belief systems may be superior. If we're only following the Bible for its message, why not look into Jainism, Buddhism or some form of humanism? Better yet, why not take the best elements from great thinkers and schools of thought across all of history? Once we decide to start cherry-picking, we might as well be thorough about it.
Ehrman goes on to emphasize the importance of the historical-critical method. In order to understand the Bible, it's imperative that we understand the culture and worldview of the authors. As an example, he mentions Jesus' ascension into heaven and his predicted return, coming down from the clouds. This makes perfect sense for writers of the time, who thought that heaven was literally a place above the sky, but no sense for educated modern readers who know that the vastness of space envelops the earth in all directions.
In his conclusion, Ehrman explains that studying the Bible is important whether it's true or not: it's vitally important within human history, it's revered among over 2 billion Christians worldwide, and it's massively misunderstood. And on this point, I completely agree. What's more, I believe that if all Christians took his advice, carefully and open-mindedly studying the Bible's errors and contentious history, Christianity as we know it would quickly vanish.