How a Book Gets Its Title

As I am getting set to start writing my book on the Afterlife (the plan is to begin the first week of August), I am mulling over possible titles.  And just as I have been in the midst of my muddling, I have received this question.

 

QUESTION:

Dr, Ehrman, can you explain a little how you go about choosing a title for your trade books ? Is it a collaborative effort between you and your agent or publisher? Can it be a difficult process where the title can change as the book progresses . And if s...