Because Muhammad prophesied it, you see. But whatever may be the objective merits of that prophecy (i.e., none), the fact that this imam in Canada believes it, and other Muslims believe it, make the prospects of peaceful coexistence on a longterm basis between Muslims and Christians in Europe dim at best.
Canada Friday Sermon by Imam Shaban Sherif Mady: Rome Will Be Conquered like Constantinople Was,” MEMRI, February 16, 2016:
During a Friday sermon delivered in Edmonton, Alberta, Sheikh Shaban Sherif Mady said that just as Byzantine Constantinople had been conquered, Rome would be conquered, as the Prophet Muhammad had prophesized. The sermon was posted on the Internet on February 16.
Imam Shaban Sherif Mady: “The Prophet Muhammad told us that Constantinople would be conquered. This was the capital city of the Byzantine Empire. I am talking about prophecies from the sunna. Where is Constantinople, the capital city of the Byzantine Empire? Today, it is in Turkey.
“Turkey, Montenegro, Kosovo, all the way to Bosnia and Herzegovina and Serbia… All these countries were ruled by the rightly guided Caliphate, the last Caliphate of the Muslims. [It ruled] about half of Europe, in the East, and then the other half, in the West, the countries of Al-Andalus: Spain, Portugal, and part of France, all the way to the Ural Mountains. All this was an Islamic Caliphate.
“Constantinople will be conquered. It is the Prophet Muhammad who said so. And what was Constantinople? Just like the Vatican today, it was the capital of all the Christians in the world. It was conquered and became Turkey. The Hagia Sophia became a great mosque, where Allah is worshipped.
“The prophecies of the Prophet Muhammad came true. But some prophecies have not come true yet. Look forward to it, because the Prophet Muhammad said that Rome would be conquered! It will be conquered. Constantinople was conquered. Rome is the Vatican, the very heart of the Christian state. When and how? You and I, who suffer of psychological defeatism, cannot fathom that. But people of faith have will, power, and understanding, and they know that the Prophet’s hadith is true, for he does not speak on a whim.”