To some, it is now unthinkable for Notre Dame or the Basilica of the National Shrine to share the fate of Hagia Sophia. But with patience, time, and commitment all things are possible.

An icon of the Blessed Mother looked down on me, then an atheist and former Muslim, as I visited Hagia Sophia years ago. The nave was so high that back in the day nearby residents would hide in the great building when Constantinople shook with earthquakes. Why? Because they believed that angels must be holding up the centuries-old cathedral for there were no columns to support the massive dome. It was impossible not to be impressed with the shimmering gold of the walls and the solemn, dignified faces of frescoes. Everything in the former seat of the Orthodox patriarch was a reminder that an awesome God had been worshipped there.

As visitors took in the magnificence, giant circle panels inscribed with Arabic words broke the spell. “Allah” and “Muhammed” read golden swirling letters on a black background. The images of Christ, Mary, and various saints had been covered—with the exception of an image of the Theotokos in the apse. Arabic calligraphy, hung in the nave of the cathedral to remind all who the new masters were, in case you missed the minarets outside.

The Basilica of Hagia Sophia (Holy Wisdom) was built in the sixth century and has been an ancient witness to the history of the beautiful city of then Constantinople, now Istanbul. That history includes a long and sad cautionary tale of how the capital of the Byzantine Empire came to be the capital of the Ottomans.

Emperor Constantine the Great dedicated the city as the new capital of the Roman Empire in AD 330. Soon, the hills that overlooked the Sea of Marmara and the Bosphorus Strait were home to one of the most prominent and wealthiest cities in Europe. With its proximity to the Black Sea and the Mediterranean, along with important trade routes connecting the East and the West, Constantinople grew in importance: politically, culturally, economically, and spiritually. Not only did the city become a crucial center for Christianity, in time it also functioned as the last bastion against expansion of Islam.

In fact, the fame and power of Constantinople was such that Muhammad promised his followers that Muslims would one day conquer the most legendary city of his day: “Verily you shall conquer Constantinople. What a wonderful leader will he be, and what a wonderful army will that army be!” (Hadith narrated by Bishr al-Khath`ami)

When Muhammad made this covetous prediction, Constantinople and the Byzantine Empire were at the highest point of their power and wealth. That began to lessen in many ways by the 11th century, and continued to diminish when the city was hit by the Black Plague, ransacked during the Fourth Crusade, and the Empire became increasingly unstable. Despite its weakened state, the legendary Theodosian Walls remained impenetrable until the reign of Mehmed II (1432-81), the Ottoman Sultan who would fulfill Muhammed’s centuries-old promise.

It was not hard for Emperor Constantine XI Palaiologos (1405-53) to deduce Mehmed’s intentions, since the 21-year-old sultan had been taking measures to secure the traffic in the Bosphorus and blocking off any possible aid Byzantine emperor might receive. Constantine turned Europe for help, but centuries of fighting was about to prove fatal for the outmost defense of Europe.

Yes, the population of city and the power of the empire had diminished through the centuries, but had the Europeans united their might, the Ottomans would not have been able to succeed, as the Battle of Lepanto demonstrated over a century later, in October 1571. However, the deep divide between the West and the East, and the resistance of European kings to come under the pope’s rule, bore bitter fruit.

By the time Sultan Mehmed completed the construction of Rumelian Castle along the Bosphorus to control the sea traffic in anticipation of a siege, Constantine knew that without help from the West the fall of his capital was imminent. He wrote to Pope Nicholas V, who reigned from 1447 to 1455, who did not have as much influence over the kings and princes of Europe as the emperor hoped. England and France were weary from the Hundred Years’ War, while Spain was still struggling with Reconquista. German tribes were far from being united, and Hungary and Poland were in the process of recovering from a significant defeat against the Ottomans in 1444. Whatever the Pope could muster from the mess of Europe was not nearly adequate enough to counter the Ottoman Army at its best.

Still, Constantine XI and the meager troops from the West did all they could to secure the city against both ground and naval attacks. The Golden Horn, an inlet into the city, was chained to prevent Ottoman galleys from entering, and the Theodosian Walls were fortified. However, no amount of preparation was sufficient to hold the Ottoman troops at bay.

After long weeks of siege and land war, the Ottoman army broke through the impenetrable walls of Constantinople with massive cannons that could fire 600 pound balls, and with galleys that were pulled into the Golden Horn over wooden oiled tracks. The young sultan was adamant to conquer New Rome, and he did so on May 29, 1453.

The city was sacked for three days. Thousands of Christians were murdered and raped, as ancient churches of the city were plundered, their altars were stripped. Hagia Sophia was turned into a mosque quickly, and many other churches followed suit.

“Well, all these happened almost 600 years ago,” one might say, “and things are different now.” A visit to Istanbul on May 29th would suggest otherwise. The Conquest of Istanbul is one of the proudest, if not the proudest, moments of Turkish history—even more so than the sultan’s acquisition of the caliphate. On the anniversary, a replica of the Janissary marching band performs as many onlookers are moved to tears. It is the Ottoman Empire’s greatest accomplishment—not because a strategic port was captured, but because Muhammad’s promise was fulfilled, opening wide the gates of Europe to Islam. As the Poles and the Hungarians would tell you, following centuries witnessed many more battles with Muslims, now even more formidable with the riches and the strategic location of Istanbul.

Today, this city near where the Councils of Nicaea and Chaldea were held boasts around 3,000 mosques. Its population, reaching almost to 15 million, is predominantly Muslim. Even though the palace is no longer the seat of caliphate, religious freedom has suffered greatly, pushing non-Muslims into survival mode. Once the Ottoman Sultans firmly established their presence in Europe, they used the division among Christians by pressuring the Orthodox Patriarchate in Istanbul and supporting Protestant Princes against Rome. Nowadays, there is constant tension between the Turkish government and Catholic, Orthodox, and Protestant churches.

The unequaled conquest of Istanbul is an inspiration to those who mean to further the cause of Islam, and it should be a cautionary tale for Christians and the West. The events that led to May 29, 1453 are eerily reflective in many ways of what has been happening in recent years.

First, of course, there was the infamous conquest of Constantinople during the Fourth Crusade, which left a ransacked city and a weakened empire in its wake. This Crusade, like the others, began as a defensive war to free the Holy Lands in the 13th century, but a series of bad decisions resulting from lack of resources led to Christians fighting Christians, first in Zara and then in Constantinople despite Pope Innocent’s protests.

The tension and fighting among Christians created divisions so deep, that by the time Emperor Constantine XI asked for help, as noted already, it was too late to fix the damage to save the imperial capital. The union that came in December 1452 meant the emperor died defending his city in full communion with the Catholic Church. But Mehmed knew well enough not to let the union stick after the conquest, and installed a Greek Orthodox patriarch who was hostile to Rome.

It was, then, division and disobedience within Christendom that rendered the West vulnerable to attacks from Muslim rulers. After all, the Ottomans did not single out Christians for their territorial ambitions. By the time the sultans reached Constantinople, they had brought many a Muslim ruler to the knee. Of course, no other city, except Rome itself, was as important to conquer as Constantinople, but were the people of the West be able to at least unite against Ottoman attacks the fate of New Rome might have been different. 564 years have since passed, and the West has many of the same shortcomings with different actors. Instead of kings and princes who fight each other, we have sovereign nations who cannot even agree on simplest definitions, let alone policies. Centuries of splintering within Christianity, the rise of secularism, and various ills of modernism have insured that agreement on common culture and goals is very difficult at best, if not impossible. In contrast, even while Islam itself has many factions, Islamic ideology offers a sense of belonging, a clearly defined moral code, and something to die for. Meanwhile, Western leaders and the dominant culture are often muddled and confusing, standing for little beyond a technocratic status quo that does little to engender loyalty and trust.

The Emperor Constantine XI did not, to be fair, make the mistake of underestimating the forces of Sultan Mehmed. But he and many other rulers before him trusted completely in the thick wall the city sat behind safely for centuries. The Atlantic Ocean has been the Theodosian Walls for the United States. For many on the Left, the great distance between seems to symbolize their historical amnesia; the lessons of the past are forgotten, belonging to an era long gone and far away. They believe that the Polish and Hungarian resistance to Muslim immigration is nothing but misguided fear and racism, forgetting that not everyone’s memory is as weak or corrupted. This historical amnesia leaves the Left in the West completely defenseless in their ignorance and naiveté. As the journalists and intellectuals on the Coasts look toward Europe and the Middle East, the vast ocean blurs their vision, making them see nothing but poverty and lack of education. History and human nature mean little to them, except to represent what needs to be remade according to their enlightened vision.

The political Right, however, is also not immune to a false sense of security. Some think immigration policies, increased surveillance, and military might will save them from the oncoming storm. But every wall is impenetrable—until a big enough cannon is cast. No matter how much immigration is regulated, without a society that is built around Christ and supported by His Church, Islamic ideology will inevitably seep in. The demanding (if often misguided) values, tight-knit community, sense of belonging, and strong masculinity Islam offers will all be part of the 600-pound cannon ball that will breach the tightly secured borders. This is not to say that a nation must not defend its borders; this is to remind the Right that the walls they so desperately try to fortify are doomed to fall because of the weakness from within, not because of the strength from without.

It was once unthinkable for Constantinople to fall into Muslim hands. Actually, a few centuries prior, there were no Muslims anywhere near. To some, it is now unthinkable for Notre Dame or the Basilica of the National Shrine to share the fate of Hagia Sophia. But with patience, time, and commitment all things are possible. Just as Sultan Mehmed sent in thousands upon thousands of his troops through the wall breaches until Constantine’s forces were utterly spent, in this new version of jihad, more and more pamphlets, videos, ideas, and big families will breach the weak walls of the post-Christian West.

Still, not all is lost. We should take heart from the Battle of Lepanto, where Our Lady herself delivered the good news of victory to Pope Pius V. When we throw the acedia of secularism and the lukewarmness of relativism aside and work to renew the Church and rebuild a Christian culture, there is no accounting to what kind of mighty tree will grow from the tiny seeds we offer. So, let the Fall of Constantinople be a cautionary tale to our often forgetful ears to remind us that while there is nothing new under the sun, only the Son can deliver us from the unrelenting horde of our age.