After the resurrection of Jesus, the spread of Christianity was rapid. Today millions of Christians exist and there isn’t a notable increase in the spread of Christianity, why?

I would say there are many reasons. I don’t think I could give an exhaustive answer to that question–it would probably take a full book–but maybe we can take a brief look at history with “theological eyes.”

St. Thomas Aquinas once commented that the initial spread of Christianity was in itself a miracle. Twelve rowdy, uneducated, and frightened men were completely transformed by the power of the Holy Spirit to spread the message of Jesus Christ to the ends of the known world. Save for St. John, all of them even died for that message and for Jesus Christ–the same Man which they had all abandoned before. The rapid spread of Christianity is a testament to the power of the Resurrection and the Holy Spirit in the hearts of just a few souls who are open to being transformed by grace.

After this initial spread under the Apostles and the first Christians, the Church then faced several centuries of persecution and social exclusion under the Roman Empire. Being a Christian was not easy in its first 200 years: there were risks. Professing belief in Jesus Christ could mean losing everything you owned or even being put to death. But as the Church Fathers would say: “The blood of the martyrs is the seed of the Church.” Christianity has a way of blossoming under trials and persecutions. The heroic witness of the martyrs inspires and gives grace. Even when the early Church was not under persecution, the heroic examples of the martyrs and other saints inspired people to leave the life they knew and choose to live for Christ.

Eventually, Christianity was legalized and soon after made the official religion of the Roman Empire. This marks a slow turning point in the history of the Church. For many centuries afterward in the Western world, entire countries (many of which descended historically from Rome) would adopt Christianity as a way of life. Before, during, and after the fall of Rome, Christianity would become the “heart” of civilization. Society was built around the Church. That is why so many core elements of Western culture originated in the Church: music, art, universities, science, philosophy, etc.

Christianity would also continue in parts of the Eastern world as well, especially in places like the Byzantine Empire (which was a continuation of the Roman Empire in the Greek world), the Middle East, and even beyond in central Asia and India. This was due to continued missionary efforts, the heroic virtue of the saints, and endurance under trials and persecutions. The spread of Christianity in the East eventually halted, but many of the places where it took root have Christian populations even today.

In later centuries, the discovery of new lands would prompt Christian nations to spread the Gospel. Missionaries from countries like Spain, Portugal, and France would carry the Gospel to far-flung corners of the world like North and South America, Japan, China, Indonesia, the Philippines, and more. Although the native peoples were often treated cruelly by conquerors from these same nations, the seeds of the Gospels would be planted deep in some of these lands. These are some of the most Catholic regions of the world today.

Eventually, though, we come to the modern age, and here the spread of the Gospel seems to hit a snag. What happened? Well, this is a consequence of many social, cultural, religious, and philosophical factors coming together, but in simple terms, society tried to construct a world in which we no longer needed God or the Church. The consequence was that Christianity was no longer seen as the “heart” of civilization. This led to the rise of modern atheism, secularism, and relativism.

We live today in a “post-Christian” world. What this means is that many places of the world have heard the Gospel, accepted it, and forgotten it. These places have “moved on” from Christianity–they have forgotten the joy of the Gospel. St. John Paul II (and every pope since) said that in response to this, we Christians are left with a task which is both old and new. Like we have done from the beginnings of the Church, we are called to preach the Gospel and to evangelize. But we are called to do this in a new way: a new evangelization! Some people today have really never heard the message of Christ, and we have a mission to them. Others, however, have heard the message but have taken it for granted and just don’t care or understand its significance. This is where we need to come in and re-evangelize the world, to help the world rediscover the goodness, love, and glory of God revealed in Jesus Christ.

This mission can be challenging for us as Christians, and perhaps this is also part of the reason why the Gospel is not spreading today like it did before. We can also take our faith for granted and be “too comfortable” with it. Maybe the trials and concerns of the world hold us back. If that’s the case, let’s look to the examples of saints past and present to inspire us! There were more Christian martyrs in the last 100 years than in the entire history of Christianity put together! Men and women around the world continue to bear witness to the faith by their words, their deeds, and even their blood. Most likely, we will not be called to die for the faith. However, we are still called to live a life for Christ! Let us pray to become like the first disciples at Pentecost and be truly transformed by the power of the Holy Spirit, to spread the Gospel like they did. We know from their example that God can transform the world with just a few souls who live for love of him. If we live a life led by the Holy Spirit, we can and will truly win the world for Christ!