Marian devotion is the cure for heresy and the healing of all heretics. We must turn to her for refuge from the heretical depravity now consuming the Church. Marian devotion is the destruction of error, the fount of humility, and a potent safeguard for orthodox faith.
Mary Is the Destroyer of All Heresies
In True Devotion to Mary, St. Louis de Montfort writes:
The most infallible and indubitable sign by which we may distinguish a heretic, a man of bad doctrine, a reprobate, from one of the predestinate, is that the heretic and the reprobate have nothing but contempt and indifference for our Blessed Lady, endeavoring by their words and examples to diminish the veneration and love of her. (30)
In the Tract for the Mass Salve Sancta Parens, the Church sings, “Rejoice, O Virgin Mary, thou alone hast destroyed all heresies.” From this, Pope St. Pius X invoked her as “Destroyer of Heresies” in Pascendi 58. And again, it was in the context of St. Dominic’s war against heresy that the Holy Rosary, Mary’s psalter, was revealed.
Thus, it is manifest that Our Lady holds a special place in the relationship of Holy Church with heresy and heretics. Why is this? It is because the root cause of heresy is not anger, lust, or sloth, but pride. A formal heretic pridefully and obstinately rejects the authority of the Church and the authority of the Fathers. His whole opinion hinges on an imaginary antiquarianism created by his pride. And it is against the sin of pride that Our Lady most perfectly shows her power. This is why St. Louis says in another place:
[Satan] fears her not only more than all Angels and men, but in some sense more than God Himself … because Satan, being proud, suffers infinitely more from being beaten and punished by a little and humble handmaid of God, and her humility humbles him more than the Divine power. (True Devotion, 52)
Demons and heretics fear her because she threatens to humble them. The latter impiously attack her under the pretense that they are safeguarding the honor due to God. In reality, they know that Mary will destroy their prideful opinions. “Humility is an abomination to the proud ” (Ecclus. 13:24).
How Mary Humbles the Proud
When the Holy Spirit exalted Mary by the mouth of St. Elizabeth, Mary said:
He hath shewed might in his arm: he hath scattered the proud in the conceit of their heart. He hath put down the mighty from their seat and hath exalted the humble. (Lk. 1:51)
Devotion to Mary brings humility to the soul. Just as St. John heard her voice and leaped for joy, and St. Elizabeth immediately humbled herself, saying “Who am I that the mother of my Lord should come to me?” (Lk. 1:43), we too know this humility when we exalt Mary.
Mary humbles us because God wills that Jesus Christ be manifested to the world through her. According to nature, any man is her equal. According to grace and merit, she is “more honorable than the cherubim, and beyond compare more glorious than the Seraphim” . In Mary, our humility is truly tested because she is a human, not God.
Humility toward God is presumed by all, and heretics falsely think themselves humble because they say they submit to God. But their pride is revealed when they refuse to submit to man — both legitimate authority and the sayings of the wise. “The way of a fool is right in his own eyes: but he that is wise hearkeneth unto counsels” (Prov. 12:15).
A humble man may even debase himself before wicked men, as our Lord did. But heretics have no humility toward men. In reality, heretics are attempting to impose their private opinion on all authorities. They have no humility toward any human but are consumed in their own selves. As the history of Protestantism has shown, it is easy to feign humility toward God while exalting yourself over every man. This is the way of all the heretics.
One who is humble toward Mary will be humble toward authority. Mary especially checks the pride of heretics by proclaiming that they cannot have their own private, “personal Jesus,” since our Lord has forever bound Himself to His mother by His incarnation. In the same way that the Incarnation is the foundation of our redemption — without which there can be no Passion or Resurrection — the human person of Jesus Christ cannot exist without the person of Mary . As I have written in another place, true union with Christ will result in love of Mary as our mother, who was also the first natural cause of His appearance to the world.
Marian Devotion is a test for orthodoxy
Since Marian Devotion is the fount of humility, it becomes a powerful test for orthodoxy. For example, when St. John Vianney’s lack of intelligence presented a barrier to his ordination, he was evaluated like this:
The vicar-general asked the superior of the seminary: ‘Is young Vianney pious? Is he devoted to the Blessed Virgin?’ The authorities were able to assure him fully upon these points. ‘Then,’ said the vicar-general, ‘I will receive him. Divine grace will do the rest.’ 
And so the Church ordained the future patron of parish priests. Sometimes it is as simple as asking if a man has Marian devotion. If a man is truly devoted to our Lady, he can be no heretic. St. Louis again:
“If you follow her,” says St. Bernard, “you cannot wander from the road.” Fear not, therefore, that a true child of Mary can be deceived by the evil one, or fall into any formal heresy. There where the guidance of Mary is, neither the evil spirit with his illusions, nor the heretics with their subtleties, can ever come — Ipsa tenente, non corruis. (True Devotion, 209) 
Thus, it is unsurprising that when we read through Building a Bridge by James Martin, S.J., a book purported to be about mercy and compassion, not a single page mentions the Mother of mercy and compassion. In fact, on page 130, he even erroneously asserts that at the Resurrection, Mary Magdalene was the first Christian, implicitly denying our Lady and the entire tradition of her Saturday memorial in which her sole faithfulness is commemorated. The examples of his warped or deficient Marian piety are only too easy to find .
But it is even more disturbing when we read how the Rhine group at Vatican II successfully suppressed the document on the Mother of God, relegating it, by a narrow vote, to the final section in Lumen Gentium (against the protests from Eastern Catholic bishops and others) . When their efforts to suppress Marian devotion were opposed by Paul VI (to his credit), the time became known to them as “Black Week” . Perhaps more alarming, Ratzinger himself admits that his Marian piety was weak in Last Testament and seems to imply the false dichotomy that Marian piety is not Christocentric . Without succumbing to the sin of rash judgment, it is nevertheless suggestive that this lack of Marian piety correlates with an apparent hubris on the part of many Vatican II “reformers.”
Whatever the true state of these and other men with an apparent reluctance to love and honor their own mother, we can be certain that our Blessed Lady is a sure refuge from heresy. As Fr. Ripperger has stated, without a strong intellectual formation, everyone becomes a Modernist in our corrupt society. That is why we must cling to Our Lady for refuge from heretics and heresy in our time.
True devotion to Mary keeps us safe from the excesses of pride. Even more in our day, let us consider: she stood firm, though she witnessed the Passion and death of our Lord. We also must stand firm, even as we are witnessing the passion and death of the Church. Moreover, it seems clear from her frequent apparitions since the 19th century that Our Lord has purposed His mother for a special role in resolving this crisis. Let us pray our daily rosary and make the First Saturdays. Let us abide with Our Lady in the Passion of the Church and never lose hope for the Glorious Resurrection.
 Eastern Catholic Marian antiphon
 So too the mediation of the Sacraments — through another human — we receive our Lord.
 It should be noted that Marian devotion is not an infallible test for orthodoxy, but merely a general rule against which there can be significant exceptions. Some Protestants, although material heretics, are in fact humble, and some Catholics are orthodox with little or no Marian piety. However, no man can be truly devoted to Our Lady and be a heretic. Moreover, formal heresy is defined as an error in the intellect and an obstinate will. It is particularly the latter from which Mary keeps us safe.
 I refuse to expose the reader to any further abuse of Our Lady from James Martin. Suffice it to say I have searched in vain for a substantial treatment or promotion of Marian devotion from Martin, and he admits in My Life with the Saints, p. 345ff., that his Marian devotion, which was shallow in his youth, was formed by the Jesuits as an imitation model, not the traditional, primarily mediatrix role. If his Marian devotion does go beyond sentimentality, let him publicly and explicitly disavow every heresy of which he is accused.
 See Rev. Ralph Wiltgen, The Rhine Flows into the Tiber (Augustine, 1979), 90ff.
 See Ibid., 234ff. The Rhine group was opposing Paul VI’s honoring of our Lady as “Mother of the Church” as well as his actions regarding collegiality, religious liberty, and ecumenism.
 See Benedict XVI, Last Testament, trans. Jacob Phillips (Bloomsbury, 2016), 70ff. As I have read more into Ratzinger, despite his obvious strengths, more of his theology has concerned me. This point was another red flag.