The Immaculate, Vanquisher of all Heresies
By Roberto de Mattei | 10 December 2025
To speak of our Lady is never repetitive. For the human intellect, speculation on her greatness is inexhaustible, because She, though a creature, is a perfect reflection of God’s immense greatness.
The truth of the Immaculate Conception was proclaimed as an infallible dogma of the Church by Blessed Pius IX on 8 December 1854, with the bull Ineffabilis Deus, with which the pope defined that the Virgin Mary was preserved from original sin from the first instant of her conception.
The foundation of this Marian privilege lies in the absolute opposition, the infinite irreconcilability, between God and sin. In contrast with man, conceived in sin, is Mary, conceived without shadow of sin, most pure and spotless. And since sin is a disorder of the intellect and will, to Mary, as the Immaculate, it is reserved to conquer every evil, error and heresy that arises and develops in the world as a consequence of sin.
At the time Mary was conceived by St Joachim and St Anne, the Roman emperor Augustus reigned and Palestine was under the rule of King Herod the Great, but humanity was steeped in sin, beginning with the Jewish people. Mary’s birth illuminated history and constituted the precondition for the birth of Christian civilisation. Through Mary, in fact, the Redeemer of humanity came into the world, and from His blood shed on Calvary there was born, on the ruins of the Roman Empire, the Holy Roman Church, the mother of the great medieval Christian civilisation.
When Pius IX ascended the papal throne in 1846, a centuries-old Revolution aimed at destroying the Christian social order was coming to a head. One of its ideological foundations was the denial of original sin. The naturalistic and rationalistic liberal and socialist system held, in fact, that the greatness and progress of man were the supreme goal of history and that modern man had to become self-sufficient and “come of age”, freeing himself from the tutelage he had until then received from the Church.
The great Spanish thinker Juan Donoso Cortés, consulted, like many others, by Pius IX on the appropriateness of defining the dogma of the Immaculate Conception, responded in these terms:
“The denial of original sin is one of the fundamental dogmas of the Revolution. To suppose that man did not fall into original sin is to deny, as is denied, that man has been redeemed. To suppose that man has not been redeemed is to deny, as is denied, the mystery of the Redemption and the Incarnation, the dogma of the external personality of the Word and the Word Himself. To suppose the natural integrity of the human will, on the one hand, and not to recognise, on the other, the existence of any evil and any sin other than philosophical evil and sin, is to deny, as is denied, the sanctifying action of God upon man and with it the dogma of the personality of the Holy Spirit. From all these denials comes the denial of the sovereign dogma of the Holy Trinity, the cornerstone of our faith and the foundation of all Catholic dogmas.”1
Fifty years later, commemorating the “day of incomparable joy” on which Pius IX had promulgated Ineffabilis Deus, Pope St Pius X, in his magnificent encyclical Ad diem illum laetissimum, once again proposed the dogma of the Immaculate Conception as an extraordinary antidote to the “flood of errors” of the “enemies of the faith”, stating:
“They begin by denying that man has fallen by sin and been cast down from his former position. Hence they regard as mere fables original sin and the evils that were its consequence. Humanity vitiated in its source vitiated in its turn the whole race of man; and thus was evil introduced amongst men and the necessity for a Redeemer involved. All this rejected it is easy to understand that no place is left for Christ, for the Church, for grace or for anything that is above and beyond nature; in one word the whole edifice of faith is shaken from top to bottom. But let people believe and confess that the Virgin Mary has been from the first moment of her conception preserved from all stain; and it is straightway necessary that they should admit both original sin and the rehabilitation of the human race by Jesus Christ, the Gospel, and the Church and the law of suffering. By virtue of this Rationalism and Materialism [are] torn up by the roots and destroyed, and there remains to Christian wisdom the glory of having to guard and protect the truth. It is moreover a vice common to the enemies of the faith of our time especially that they repudiate and proclaim the necessity of repudiating all respect and obedience for the authority of the Church, and even of any human power, in the idea that it will thus be more easy to make an end of faith. Here we have the origin of Anarchism, than which nothing is more pernicious and pestilent to the order of things whether natural or supernatural. Now this plague, which is equally fatal to society at large and to Christianity, finds its ruin in the dogma of the Immaculate Conception by the obligation which it imposes of recognizing in the Church a power before which not only has the will to bow, but the intelligence to subject itself. It is from a subjection of the reason of this sort that Christian people sing thus the praise of the Mother of God: ‘Thou art all fair, O Mary, and the stain of original sin is not in thee.’ (Mass of Immac. Concep.) And thus once again is justified what the Church attributes to this august Virgin that she has exterminated all heresies in the world.”2
Our Lady, therefore, as she stands out against the grandiose backdrop of Ineffabilis Deus, is the “glorious vanquisher of heresies” of which all the pontiffs speak, and the contrast between the “all beautiful and Immaculate” Virgin and the “most cruel serpent” makes manifest the first and fundamental agents of the radical antagonism between the Church and that Revolution of modern times that has its most active and deeply rooted seeds precisely in the disorder of the passions and the intellect, father of every error and heresy and fruit of the sin of fallen man.
Against this backdrop is situated the struggle between the Church and the Revolution, which today rages more violently than ever and could be called a mortal struggle, if one of the contenders were not immortal.
Notes