Closet Atheists can be hiding just about everywhere!
Just imaging being Pope and suddenly realising it's all been a lie. What would you do? Give up all that wealth, adulation and power, and the servants who come with the post, or would you be honest to yourself and to everyone else?
The Catholic Church had survived schisms, multiple papacies, corrupt gangsters, debauched gluttons and thieves, violent psychopaths, murderers and even (allegedly) a female imposter Pope, but could it survive an honest Atheist Pope, or would world-wide Catholicism shatter and crumble if an honest Pope told the world that he had come to realise that the 'faith' was founded on lies and that Jesus was just a myth based on Bronze-age superstitions and stories concocted for political purposes.
[Update] A couple of weeks after I posted this, Pope Benedict XVI announced his resignation, citing, amongst other things, "hard questions of faith". I'm sure it must have been a coincidence...