Saint Margaret Mary Alacoque (1647-1690) is the apostle and confidante of the Sacred Heart of Jesus. The mystical experience in which she was the protagonist left the Church a precious legacy: the great promise, the source of the subsequent devotion of the nine First Fridays of the month. There is no doubt about the authenticity of this promise, so much so that Benedict XV, in a highly unusual move, included it in the bull of canonization of Saint Margaret Mary Alacoque.

These are the words the Lord gives to Margaret as he shows her his heart surrounded by flames:
“I promise you, in the excessive mercy of my heart, that my almighty love will grant to all those who receive Communion on the first Friday of the month for nine consecutive months the grace of final repentance (that is, eternal salvation). They will not die in my displeasure, nor without receiving the sacraments, and my heart will be their safe refuge in that final hour.”
Jesus grants eternal salvation to anyone who, with the proper dispositions, receives Holy Communion on the first Friday of the month for nine consecutive months.

We truly stand before an exceptional promise; it seems like a secure insurance policy on life... eternal life! But we must be careful and remember that there is not, and never can be, anything magical or automatic about it. We know from Revelation that every gift from God, every grace of his, always presupposes man's response in obedience to his will. 
The great promise reveals the mystery of the heart of a God who is moved and pours out all his love upon humanity, but above all it shows that each of us can experience and savor the tenderness of this love; each of us can allow ourselves to be enveloped by the humble fidelity and gentleness of the love in Christ's heart. 

It is clear that, in the promise made by Jesus, final salvation is the exclusive work and gift of the Father's great mercy, manifested through the heart of Jesus, who awaits man's free response. The initiative of his love calls us to account. We are called every day, not just once a month, to cooperate by committing ourselves to a journey of conversion.