In the middle of the third century A.D., a catastrophic plague swept the Roman Empire, claiming as much as one-third of the population in some regions.

“All were shuddering, fleeing, shunning the contagion, impiously throwing out their own friends … there were bodies lying all over the city … well, not bodies anymore, but carcasses, demanding the pity of passers-by the contemplation of a fate that would soon be theirs,” is how a contemporary witness described it.

While everyone was running from the disease, the members of a relatively small and persecuted sect were not. At the orders of their bishop, Cyprian, Christians in Northern Africa went into the streets to look for the sick, without regard for the religion or social status of the stricken. They could not cure the disease; in fact, most of the time, they contracted it and died themselves.

And yet, their actions changed the course of history.

Before and during the plague, Christians in the vast Roman Empire had been persecuted. But after the plague, the Church’s numbers grew exponentially: the plague had shown that Christians could do what no one else could. Not only were they not terrified by death, but they were ready to give up their lives for their persecutors.

These and other scenes are explored in Mike Aquilina’s new book, “The Church and the Roman Empire (301–490),” part of his series “Reclaiming Catholic History.” As Aquilina puts it in the book’s introduction, every age is pivotal, in the sense that it marks a transition into something else. 

But this age was marked by the two single most momentous transformations in the ancient world, namely the Church’s transition from negligible sect into the religion of the Roman Empire, and the decline and eventual fall of the Western Roman Empire (476 B.C.)

It is a terrific book: fast, engaging, suspenseful, interspersed with novel-like dramatic sections and fact-checking boxes to debunk common myths about the early Church. Aquilina zooms in and out of Church history with remarkable ability for synthesis and a style that is both simple and direct. 

Along this exciting journey we meet the likes of Constantine, the emperor who first granted Christians freedom to worship and the great Church Fathers Basil, Ambrose, Jerome, and Augustine. 

We witness the world’s astonished reaction to the sack of Rome (410 B.C.) and we wonder about the mysterious words used by Pope Leo to persuade Attila, the leader of the Huns, not to attack the city of Rome.

All that may sound like a nice sequence of interesting historical details. But, when it comes to ancient Church history, why should we care?

In his famous 1997 book “Salt of the Earth” (Ignatius Press), the future Pope Benedict XVI memorably captured the similar historical transition that the Church is experiencing in this generation. 

“Maybe we are facing a new and different kind of epoch in the Church’s history, where Christianity will again be characterized more by the mustard seed, where it will exist in small, seemingly insignificant groups that nonetheless live an intense struggle against evil and bring good into the world,” then-Cardinal Joseph Ratzinger said. 

In other words, Ratzinger prophesied, the Church is on its way back to precisely the period that Aquilina chose to cover in “The Church and the Roman Empire.”

During the age of Constantine, the Church moved from being small, persecuted, and perceived as essentially incompatible with the political order of the Roman Empire to becoming the empire’s religion. Today, we witness the reverse: the Church’s relevance in the world of culture and politics fades, numbers dwindle, and persecution looms on the horizon.

That’s why Aquilina’s book is not only a treat for history buffs, but an important resource for even the most ordinary Catholics to think more deeply about where the Church is today and where it may end up tomorrow. 

Take the Arian controversy, which Aquilina addresses in the book’s third chapter. This powerful heresy basically tore the universal Church apart for nearly two centuries. 

As Benedict XVI described it, the heretic Arius “threatened authentic faith in Christ, declaring that the Logos was not a true God but a created God, a creature ‘halfway’ between God and man who hence remained forever inaccessible to us.”

The doctrinal battle between supporters and opposers of Arius climaxed in the great showdown of the Council of Nicaea, in which Arius was trashed by St. Athanasius (we owe to this council the Nicene creed, the one recited every Sunday at Mass).

It’s a controversy that may seem abstract and pedantic, the kind of hair-splitting that interests theologians and no one else, but Aquilina draws attention to an interesting theory.

The idea that the one and only God, eternal, perfect and inaccessible, became man was inconceivable to philosophical pagans. “Arianism gave the pagans a kind of Christianity Lite, easy to accept without changing ingrained habits of thoughts,” Aquilina argues. 

The parallels to today’s Church are hard to ignore. The Church today is once again torn by doctrinal controversies, and is not hard to see that attempts to changing Catholic teaching very often stem from a desire to make Catholicism more acceptable to our contemporaries.

Take the church’s position on the indissolubility of marriage. Wouldn’t it be easier to attract people if the Church stopped asking people to abide by these impossible standards? And yet, attempts at ‘lowering the bar’ of Christian doctrine often disguise a lack of faith in the extraordinary event of the Incarnation.

The Church of the third century converted the masses to its teachings by showing that Christians could do what no one else could. The Christians of Africa showed that they could love those who persecuted them, even at the risk of death.

This is what “The Church and the Roman Empire” ultimately invites the reader of faith to reflect upon: that the Church best performs its mission of shining a light in the world when such radical love and charity is seen in Christians.

Aquilina’s book can help us look at the great challenges of today’s world and of the contemporary Church with the confidence that God has not abandoned his little flock, and that his plan will prevail.