Well it seems that the pope thinks that it is a "mystery" why  catholic clergy sexually abused children for centuries, "undermining the church"!!!! 
Well let me enlighten him !
There is NO  mystery why pedophiles abuse children, -that is what they do!
There is NO mystery why they enter the priesthood- that is where they are safe!
There is No mystery why they are safe- they are joining a narcissistic regime whish see itself as inviolate, infallable, and untouchable by any laws.
It is NO mystery why they have got away with it for years- the pope and his minions see it as their prime objective to make sure they do not get punished.
It is NO mystery why everyone is disgusted with you- they are fed up with being fed lies and witnessing appalling cover ups.
They is NO mystery why the churches numbers are down- your sheep are now getting wise to your dishonesty, greed and subjugation of human beings.
There is NO mystery why your conspiracy of silence is getting on everyones nerves- the world is smaller now, lots of communications, you can no longer target isolated communities safe in the knowlege that they will not be able to talk to each other.
There is certainly NO  mystery why survivors are getting stronger and more verbal- they are standing together after years of being afraid of you, and of being further abused.
There is NO  mystery why you are not welcome in the countries you deign to visit in your aptly named plane "Shepherd 1".
There is NO  mystery why those countries expect your criminals to adhere to the laws of the land, and not your man made canon law.
There is NO mystery why children who are abused by you and have suffered the worst betrayal of body and trust want an end to THEIR suffering.
What is a bloody mystery is why the hell anyone still listens to a word you say!
And it is a bloody  mystery why you are not in jail!