IT IS an almost provocative way of looking at things, but one that the pope has adopted several times. It came up yesterday when he was speaking to a delegation from Scotland about the 21 Coptic Christians from Egypt who were recently murdered by Islamist terrorists. According to Vatican Radio, he said:
The blood of our Christan brothers and sisters is a testimony which cries out to be heard...It makes no difference whether they be Catholics, Orthodox, Copts or Protestants. They are Christians! Their blood is one and the same. Their blood confesses Christ.
Today the pope followed this by praying, as he began Mass, for "our brother Copts, whose throats were slit for the sole reason of being Christian, that the Lord welcome them as martyrs...." He also prayed for the Patriarch of the Coptic Orthodox Church, "my brother Tawadros, who is suffering greatly..."


This was a passionate reaffirmation of an argument which the pope had laid out, a bit more hypothetically, in an interview with an Italian newspaper in December 2013. He said then:
For me, ecumenism is a priority. Today, we have the ecumenism of blood. In some countries they kill Christians because they wear a cross or have a Bible, and before killing them they don't ask if they're Anglicans, Lutherans, Catholics or Orthodox. The blood is mixed.
It takes a moment to explain why the pope is pushing boundaries by using this language. After a century of mostly well-intentioned dialogue between the world's Christian communities, they are still far from unity. Unresolved doctrinal differences make it impossible for, say, Catholic and Coptic Christians to share routinely in their faith's most important rite which, for believers, involves "making present" the self-sacrifice of Jesus Christ by consecrating bread and wine. When Pope Francis met the Coptic Patriarch, the pontiff yearned for the time when the two of them "will be able to drink together from the one cup"with the clear implication that the time had not arrived yet. (Only in exceptional circumstances can Catholics and Coptic Orthodox share communion.) 
Then recall that the very word "ecumenism" is both ambivalent and controversial. At its loosest, the term simply refers to emollient interactions between Christian communities. But it can also refer to the specific project of uniting all Christians in a single organisation; an idea that is viewed with extreme wariness by doctrinally conservative Protestants, Catholics and Orthodox. All these groups fear a watering down of dogmas which they hold dear. Such people see the very word "ecumenical" as a negative. 
Pope Francis is himself conservative enough to see that those problems, baffling as they may be to outsiders, run too deep to be solved overnight. But he is throwing out a challenge. People who cannot come together for a ritual of sacrifice in a church are being cast by circumstances into a single, dire community of fate. In one sense, that very fact renders their differences irrelevant. It also challenges people living in safer circumstances to work harder on tearing barriers down.