Over the centuries, the Catholic Church has seen many of her children rebel against her with all sorts of bad ideas, blasphemies, and outright heretical statements. The list is long (too long, sadly) and includes such heresiarchs as Marcion, Arius, Pelagius, Luther, Calvin and many more. These men and their followers greatly damaged the unity of the Church, and we still see the effects in various different ways to this day.

All Christians are to be one body, just as the Son and the Father are one (cf. John 17:21). Unfortunately that hasn’t been the case for centuries. How are we supposed to expect the world to believe that the Father has sent the Son if we all contradict each other? The rebel children of Holy Mother Church make for a misleading witness to the masses who have yet to come to a conversion of heart. 

Not all rebellions against the Catholic Church started inside the Church, but some happened outside. One in particular, which is still with us to this day, is Mohammedanism, more commonly known as Islam. This “revolt”, of sorts, greatly twisted the truths found in Christian (and even in Jewish) theology. Catholic author and historian Hilaire Belloc called Islam “the great and enduring heresy of Mohammed”. It would be good to shed light on what he means here, and what such an assertion means for us as Catholics in the twenty-first century.

What Is a Heresy?

In his book The Great Heresies, Belloc lays out the scheme of his treatment on the subject, mentioning that the full success of Islam “would have involved the destruction of the Catholic Church”. As mentioned, most attacks on the Catholic Faith started from within the Church, but Belloc notes that Islam is qualitatively different and anomalous. He observes the following:

“The Mohammedan attack was of a different kind. It came geographically from just outside the area of Christendom; it appeared, almost from the outset, as a foreign enemy; yet it was not, strictly speaking, a new religion attacking the old, it was essentially a heresy; but from the circumstances of its birth it was a heresy alien rather than intimate. It threatened to kill the Christian Church by invasion rather than to undermine it from within.”

Now it’s important to make a distinction here between heresies and heretics, and likewise, it’s important to get at the actual definition of the words “heresy” and “heretic”. First off, the Catechism of the Catholic Church calls heresy a rupture “that wound[s] the unity of Christ’s Body”. The Catechism further defines heresy as:

“the obstinate post-baptismal denial of some truth which must be believed with divine and catholic faith, or it is likewise an obstinate doubt concerning the same” (CCC 2089).

What Makes Someone a Heretic?

So a heretic would be someone who rejected or obstinately doubted a truth of the Catholic Faith after their baptism, such as Arius or Luther. However, the big qualifier is this: the modern day followers of such heretics, or of the heresies they promulgated, are not heretics themselves. The Catechism, quoting Unitatis Redintegratio (the Second Vatican Council’s decree on ecumenism) further explicates that:

“The children who are born into these communities [that resulted from such separation] and who grow up believing in Christ cannot be accused of the sin involved in the separation…”

This means that most Lutherans or Baptists we encounter today are not heretics. A heretic has to first be Catholic. All of their spiritual descendants never made a post-baptismal denial because, for most, they weren’t baptized Catholic! The term itself may be loaded in our easily offended modern culture, but words have meanings, and the term “heretic” has a very precise meaning as well.

A Twisting of Theological Truths

So how does this relate to Muslims, especially since Islam did not develop from within the Church? Belloc uses this term analogously. As seen above, Islam twists the theological truths of the Christian faith. Primarily, Islam denies that Jesus is divine; that he is God incarnate. While we as Christians understand that Christ is priest, prophet and king, Muslims only recognize Jesus as a mere prophet.

Now like our Protestant brothers and sisters, those that are born into Islam are not heretics. We do still share some commonalities between our faith, namely the belief in one God, who happens to be the God of Abraham (see Dr. Edward Feser’s treatment on this subject for a good, orthodox overview). Despite our commonalities, though, there are grave errors present in the theology of Islam, and as we’ll see in a moment, these errors originated from an amalgamation of several different theologies and religious tenets, including Arianism.

So while we can’t outright and precisely call Islam a “heresy”, we can still recognize it as such in an analogous way, as Islam denies that central doctrine of the Catholic Faith: that God became man so as to freely atone for our sins.

Indifferentism and Religious Conviction

It’s important that we as Catholics know more about what those of other faiths believe. That way we can interact with them honestly as we try to proclaim the gospel in its fullness through our daily lives. The same is true with Islam. In their book Inside Islam: A Guide for Catholics, authors Daniel Ali and Robert Spencer recognize the indifferentism that is running rampant in our culture. That is, people believing it’s not important to learn about the religious convictions of others, and also the religious indifferentism of many Christians (including Catholics) who don’t understand why it is important for Christians to introduce the gospel to non-Christians. Ali and Spencer emphatically declare that it is important that such peoples are introduced to the Truth, the Way, and the Life:

“Although there are undoubtedly millions of virtuous Muslims, Islam itself is an incomplete, misleading, and often downright false revelation which, in many ways, directly contradicts what God has revealed through the prophets of the Old Testament and through His Son Jesus Christ, the Word made flesh.”

We can clearly see that Islam is incomplete in the sense that it sees Jesus as only being man, and not God. But how did it come to be that Mohammed and his followers accepted part of God’s revelation, but not other parts?

The Birth of Islam

Islam itself has its origins in the seventh century. During the time immediately leading up to Islam’s birth, virtually all Christians were united. The Great Schism that separated the Eastern and Western Churches would not take place for another few centuries. Christians were no longer being persecuted as they had a few hundred years earlier. It was a time of relative peace.

But in the year 610, Muhammad claimed to have received revelations through the archangel Gabriel, which continued until his death in 632. Living in Arabia, he was able to come in contact with a diverse number of peoples, all belonging to different religious traditions. His own wife, Khadija, had a cousin named Waraqa bin Naufal who was a Christian monk. It was Waraqa who had confirmed to Muhammed that his revelations were true, and is thought by many historians to have had been Nestorian, which was the heresy that denied Mary was the Theotokos, or Mother of God.

Because of his interactions with Christians like Warqa, he adamantly rejected polytheism and the rampant materialism of the age. However, his contact with Christians was not limited to Nestorians. Ali and Spencer point out the following:

“Few of these Christian communities [in both Arabia and Yemen] were orthodox; most advocated one or more of the heresies of the time, including Arianism, Monophysitism, and Nestorianism. All of these heresies held false or incomplete views of the nature of Christ. As a result, he seems never to have gained a clear, orthodox understanding of the Gospel…

The Koran also denies the crucifixion of Christ… This may point to a Gnostic influence… [and] there were also some Manicheans in Arabia at this time, and they too became imbued with many of these false notions about the crucifixion.”

Nothing Original in Mohammed’s Religion

It would seem that Islam had been constructed piecemeal from various bits and fragments of different theologies. Some doctrines were accepted and integrated in their entirety, such as the oneness and omnipotence of God, yet others were rejected, such as Christ’s divinity and the inspiration of Sacred Scripture, particularly the New Testament. The Catholic Encyclopedia even goes as far to say that:

“Islam contains practically nothing original; it is a confused combination of native Arabian heathenism, Judaism, Christianity, Sabiism (Mandoeanism), Hanifism, and Zoroastrianism.”

Here’s one example of this confusion. The Koran mistakenly asserts and teaches that Christians worshipped Mary, and not the Holy Spirit, as part of the Holy Trinity (emphasis added):

“And [beware the Day] when Allah will say, ‘O Jesus, Son of Mary, did you say to the people, ‘Take me and my mother as deities besides Allah ?’ He will say, ‘Exalted are You! It was not for me to say that to which I have no right’” (Sura 5:116).

Of course, Christians have never worshipped Mary, except for a small, heretical sect in the region of Thrace called the Collyridians. So not only did Mohammed twist Christian theological ideas, but in the Koran itself, even fundamental Christian doctrine was confused with the erroneous teachings of an extremely small sect.

How Mohammedanism Endured

But what led to Islam growing so quickly? Belloc points out that Islam didn’t die out like other major heresies did, and even he realized that it is difficult to assess why this is so. I quote him at length:

“[T]he particular quality of Mohammedanism, regarded as a heresy, was its vitality. Alone of all the great heresies Mohammedanism struck permanent roots, developing a life of its own, and became at last something like a new religion… Like all heresies, Mohammedanism lived by the Catholic truths which it had retained…, [yet] it has survived for other reasons than these; all the other great heresies had their truths as well as their falsehoods and vagaries, yet they have died one after the other. The Catholic Church has seen them pass, and though their evil consequences are still with us the heresies themselves are dead.

“But Mohammedanism… flourished continually, (and as a body of doctrine is flourishing still), though 1300 years have passed since its first great victories in Syria. The causes of this vitality are very difficult to explore, and perhaps cannot be reached. For myself I should ascribe it in some part to the fact that Mohammedanism being a thing from the outside, a heresy that did not arise from within the body of the Christian community but beyond its frontiers, has always possessed a reservoir of men, newcomers pouring in to revivify its energies…

“Whatever the cause be, Mohammedanism has survived, and vigorously survived… In view of this, anyone with a knowledge of history is bound to ask himself whether we shall not see in the future a revival of Mohammedan political power, and the renewal of the old pressure of Islam upon Christendom.”

A Resurgence of the Caliphate

Keep in mind that Belloc was writing in 1938. At the time, the Islamic caliphate was seemingly far from coming back into power. But can we not see how true Belloc’s prediction is now? Many Christians, including our Chaldean and Syriac Catholic brothers and sisters, have suffered heavily in the last several years, and even some Catholics in Europe have suffered. Belloc further predicted that it seems “possible, and even probable, that there would be a resurrection of Islam and that our sons or our grandsons would see the renewal of that tremendous struggle between the Christian culture.”

Well, it looks like we are those “grandsons” in this current generation. And I think part of this “resurrection” is our fault, as many Christians in the West have completely abandoned their faith, or have become lukewarm to it. Christians, and particularly Catholics, need to be on fire for their faith and confidently proclaim the gospel wherever they are. Islam has gained many converts in the last half century, while on the other hand, we can accurately say that in the West we are “hemorrhaging” Catholics. Indeed, studies show that seventy-seven percent of converts to Islam were raised Christian.

Whereas many Muslims are unashamed to profess their faith, many Catholics are manifestly ashamed to show in any way, publicly, that they are Catholic. If we want to bring others to accept Jesus Christ as Lord and God, and if we want them to embrace truth, we must be willing to live out our Lord’s commands and “make disciples”. This witness is the only way we can hope to bring any rebel children back to the loving embrace of Holy Mother Church.

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You May Also Like:

Inside Islam: A Guide for Catholics

Abraham: Model of Faithfulness

Christendom Lost

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About Nicholas LaBanca

Nicholas is a 20-something cradle Catholic who wears many hats, (husband, father, tradesman, religious education catechist, liberal arts college graduate, et al.) and hopes to give a unique perspective on life in the Church as a millennial. His favorite saints include his patron St. Nicholas, St. Ignatius of Loyola, St. Thomas Aquinas, St. John Mary Vianney and St. Athanasius of Alexandria. He currently writes for the Diocese of Joliet’s monthly magazine, “Christ Is Our Hope”.