Yet Hilaire Belloc, a great and orthodox thinker, appears to support the teaching of the Catechism. Although he wrote well before the Catechism, he notes that Mohammedanism arose not as a new religion, but as a heresy within Christianity:
“Mohammedanism was a heresy: that is the essential point to grasp before going any further. It began as a heresy, not as a new religion. It was not a pagan contrast with the Church; it was not an alien enemy. It was a perversion of Christian doctrine. Its vitality and endurance soon gave it the appearance of a new religion, but those who were contemporary with its rise saw it for what it was – not a denial, but an adaptation and a misuse, of the Christian thing. It differed from most (not from all) heresies in this, that it did not arise within the bounds of the Christian Church. The chief heresiarch, Mohammed himself, was not, like most heresiarchs, a man of Catholic birth and doctrine to begin with. He sprang from pagans. But that which he taught was in the main Catholic doctrine, oversimplified. It was the great Catholic world – on the frontiers of which he lived, whose influence was all around him and whose territories he had known by travel – which inspired his convictions […]
He took over very few of those old pagan ideas which might have been native to him from his descent. On the contrary, he preached and insisted upon a whole group of ideas which were peculiar to the Catholic Church and distinguished it from the paganism which it had conquered in the Greek and Roman civilization. Thus the very foundation of his teaching was that prime Catholic doctrine, the unity and omnipotence of God. The attributes of God he also took over in the main from Catholic doctrine: the personal nature, the all-goodness, the timelessness, the providence of God, His creative power as the origin of all things, and His sustenance of all things by His power alone. The world of good spirits and angels and of evil spirits in rebellion against God was a part of the teaching, with a chief evil spirit, such as Christendom had recognized. Mohammed preached with insistence that prime Catholic doctrine, on the human side – the immortality of the soul and its responsibility for actions in this life, coupled with the consequent doctrine of punishment and reward after death.
But the central point where this new heresy struck home with a mortal blow against Catholic tradition was a full denial of the Incarnation.
Mohammed did not merely take the first steps toward that denial, as the Arians and their followers had done; he advanced a clear affirmation, full and complete, against the whole doctrine of an incarnate God. He taught that Our Lord was the greatest of all the prophets, but still only a prophet: a man like other men. He eliminated the Trinity altogether.
With that denial of the Incarnation went the whole sacramental structure. He refused to know anything of the Eucharist, with its Real Presence; he stopped the sacrifice of the Mass, and therefore the institution of a special priesthood. In other words, he, like so many other lesser heresiarchs, founded his heresy on simplification.
Catholic doctrine was true (he seemed to say), but it had become encumbered with false accretions; it had become complicated by needless man-made additions, including the idea that its founder was Divine, and the growth of a parasitical caste of priests who battened on a late, imagined, system of Sacraments which they alone could administer. All those corrupt accretions must be swept away.
[…] Simplicity was the note of the whole affair; and since all heresies draw their strength from some true doctrine, Mohammedanism drew its strength from the true Catholic doctrines which it retained: the equality of all men before God – “All true believers are brothers.” It zealously preached and throve on the paramount claims of justice, social and economic.”
Does Belloc’s exegesis lend enough support to the Catechism’s view that Islam and Christianity worship the same God so as to overcome the obvious problems posed by the denial of the incarnation and issues related to the Trinity which arise as a result?
Personally, I feel that Islam and Christianity differ to such a degree at the doctrinal level that I do not see how the two could describe the same God. Even if you disagree with this end conclusion, there should be little doubt that the Christian must view Islam as doctrinally flawed. The teaching of Islam on the Trinity is incorrect – The Father is God, Jesus is God and the Holy Spirit is God. The Holy Trinity is God. We know this because, while we have had a personal relationship with the Father, we have also had a personal relationship with the Son and the Holy Spirit. It is absolutely incumbent upon Christians to learn those ways in which Christian and Muslim beliefs differ, learn why they differ, and be able to defend our faith and beliefs.
Despite the above, I believe that on the personal level it may be impossible to know whether an individual Muslim worships the One God. For most people, our faith is not an intellectual exercise. It is an emotive response to the stirring of the heart. We can never be sure the degree to which any person has either turned their heart toward God, nor away from Jesus. Even for those who have been taught about Jesus, it is impossible to determine the depths to which their current religious beliefs have been instilled and to assess their capacity to be fully open to conflicting teachings. Further, surely the Muslims worship Someone, and with admirable reverence at that. Is it not possible that they may worship the God of the Trinity without awareness or an acknowledgment of the Mystery – much as a man might fall in love with a woman only to learn over time the many aspects of her beauty that he could never have discovered before they grew in intimacy? It is perhaps for this reason that the Catechism states that Muslims individually worship the One True God but does not make any assertions with regard to Islam and its teachings.
All this strengthens rather than reduces the obligation of Christians to evangelize and teach the Word. Inspired by the Holy Spirit, we must draw others to the Holy Spirit, who proceeds from the Father and the Son. We must introduce others to Jesus, through our love and compassion. However, we must do so with love, gentleness and reverence. As St. Francis said to the Sultan of Babylon: “If you wish to be converted to Christ along with your people, I will most gladly stay with you for love of Him.”
Hilaire Belloc, “The Great and Enduring Heresy of Mohammed”
Brother David Kazmarek, TOR, “St. Francis of Assisi and the Muslims”