The Sacred Heart devotion is ancient, but Christ Himself gave it a massive boost when he appeared personally to St. Margaret Mary Alacoque with a plan to revitalize the devotion.
St. Margaret Mary wrote to a friend: "He made me see that it was the great desire He had of being loved by men, and of removing them from the road of damnation, that induced Him to conceive this plan of making His Heart known to men."
And for those who renewed their devotion to His Sacred Heart, Our Lord made these twelve promises:
- I will give them all the graces necessary in their state of life.
- I will establish peace in their homes.
- I will comfort them in all their afflictions.
- I will be their secure refuge during life and, above all, in death.
- I will bestow abundant blessing upon all their undertakings.
- Sinners shall find in My Heart the source and infinite ocean of mercy.
- By devotion to My Heart tepid souls shall grow fervent.
- Fervent souls shall quickly mount to high perfection.
- I will bless every place where a picture of My Heart shall be set up and honored.
- I will give to priests the gift of touching the most hardened hearts.
- Those who promote this devotion shall have their names written in My Heart, never to be blotted out.
- I will grant the grace of final penitence to those who receive Holy Communion on the first Friday of nine consecutive months.
St. Margaret Mary wrote elsewhere that the plan was simple: "He continually burns with love for us in the Blessed Sacrament. To become saints it suffices to love this Holy of Holies."