I wonder what percentage of vicars (and others of that level and above in the various religions) are actually atheists or neo-atheists, 6 and 7 on the Dawkins scale.
Some just simply begin with total faith and gradually totally lose it. Some people in any job just do it because they are good at it and can get reasonable money and promotion prospects.
There is a facility in The Richard Dawkins Foundation For Reason & Science for including such people in the membership and helping them :- http://clergyproject.org/
I cannot recall from where I recently heard that 150 were signed up nor whether that was the full number or the number in just one country or one religion. Possibly it was Richard himself stating it on a video of unknown age.
It will probably be a few decades before we get accurate numbers on this. By that time, the people in the clergy project now will be dead, and hopefully have left instructions to tell their whole story, and more hopefully, it will be okay to be out while they are alive. There are a few.
I do like the occasional bit of mandolin.