There's a massive difference - and the Pope must surely know it - between the killings of Christians by Muslims, and killing and violence that just so happens to have been carried out by people of a particular faith.
Again, there's a big difference between killing on behalf – or because – of a religion; and the killing being carried out by someone who just happens to belong to a religion.
For example, when an Italian Catholic drug-dealer kills a rival drug-dealer, he doesn't do so as a Catholic. On the other hand, when those Muslims killed a Catholic priest in Normandy, they did so because of their religion.
And I don't give a damn about the fact that a tiny minority of Western Muslims - when talking to the Western press! - say that these Islamic killers (or ISIS) "aren't real Muslims". (Or that they've “distorted Islam".) We should judge Islam by its fruits: killing, torture, terrorism, sex-slavery and the rest.
This is so obvious that I believe the Pope himself knows the difference.
What the Pope is doing here is what people call "virtue signalling". And what can be more virtuous than signing the death warrant of one's own religion?
Piety and political correctness are going to result in the death of Western Christianity. Indeed, in the Muslim world, Christianity is already almost dead.