BLESSED ALAN DE LA ROCHE who was so deeply devoted to the Blessed Virgin had many revelations from her and we know that he confirmed the truth of these revelations by a solemn oath. Three of them stand out with special emphasis: the first, that if people fail to say the Hail Mary (the Angelic Salutation which has saved the world) out of carelessness, or because they are lukewarm, or because they hate it, this is a sign that they will probably and indeed shortly be condemned to eternal punishment.
The second truth is that those who love this Divine salutation bear the very special stamp of predestination.
The third is that those to whom God has given the signal grace of loving Our Lady and of serving her out of love must take very great care to continue to love and serve her until the time when she shall have had them placed in heaven by her divine Son in the degree of glory which they have earned. (Blessed Alan, chapter XI, paragraph 2)
The heretics, all of whom are children of the devil and clearly bear the sign of God's reprobation, have a horror of the Hail Mary. They still say the Our Father but never the Hail Mary; they would rather wear a poisonous snake around their necks than wear a scapular or carry a rosary.
Among Catholics those who bear the mark of God's reprobation think but little of the rosary (whether that of five decades of fifteen). They either fail to say it or only say it very quickly and in a lukewarm manner.
Even if I did not believe that which has been revealed to Blessed Alan de la Roche, even then my own experience would be enough to convince me of this terrible but consoling truth. I do not know, nor do I see clearly, how it can be that a devotion which seems to be so small can be the infallible sign of eternal salvation and how its absence can be the sign of God's eternal displeasure; nevertheless, nothing could possibly be more true. [Emphasis added.]
In our own day we see that people who hold new doctrines that have been condemned by Holy Mother Church may have quite a bit of surface piety, but they scorn the Rosary, and often dissuade their acquaintances from saying it, by destroying their love of it and their faith in it. In doing this they make elaborate excuses which are plausible in the eyes of the world. They are very careful not to condemn the Rosary and the Scapular as the Calvinists do----but the way they set about attacking them is all the more deadly because it is the more cunning. I shall refer to it again later on.
My Hail Mary, my Rosary of fifteen or of five decades, is the prayer and the infallible touchstone by which I can tell those who are led by the Spirit of God from those who are deceived by the devil. I have known souls who seemed to soar like eagles to the heights by their sublime contemplation and who yet were pitifully led astray by the devil. I only found out how wrong they were when I learned that they scorned the Hail Mary and the Rosary which they considered as being far beneath them. [Ibid.]
The Hail Mary is a blessed dew that falls from Heaven upon the souls of the predestinate. It gives them a marvelous spiritual fertility so that they can grow in all virtues. The more the garden of the soul is watered by this prayer the more enlightened one's intellect becomes, the more zealous his heart, and the stronger his armor against his spiritual enemies.
The Hail Mary is a sharp and flaming shaft which, joined to the Word of God, gives the preacher the strength to pierce, move and convert the most hardened hearts even if he has little or no natural gift for preaching. [Ibid.]
As I have already said, this was the great secret that Our Lady taught Saint Dominic and Blessed Alan so that they might convert heretics and sinners.
Saint Antoninus tells us that this is why many priests got into the habit of saying a Hail Mary at the beginning of their sermons.
Source: http://www.catholictradition.org/Classics/secret-rosary17.htm
