June is regarded as the month of the Sacred Heart of Jesus because the solemnity of the Sacred Heart is commemorated during this month. The solemnity falls on June 16 this year. Because it is observed on the Friday following the Corpus Christi octave or the Friday following the second Sunday following Pentecost, the exact date varies every year.
There are, however, additional reasons why June is devoted to the Sacred Heart.
The feast day originated in 1673 when a nun from the Order of the Visitation of Holy Mary (Visitandines) in eastern France started to have visions of the Sacred Heart.
With his heart visible outside of his chest, on fire, and encircled by a crown of thorns, Jesus appeared to Sister Margaret Mary Alacoque and explained how to revere his Sacred Heart and the enormous love he had for humanity.
These various ways include receiving the Eucharist on the first Friday of each month and participating in a holy hour on Thursdays.
Jesus told Sister Margaret Mary: “My Sacred Heart is so intense in its love for men, and for you in particular, that not being able to contain within it the flames of its ardent charity, they must be transmitted through all means.”
These visions persisted for 18 months.
Jesus then instructed Sister Mary on June 16, 1675, to spread the word about a feast honoring his Sacred Heart. Additionally, Jesus handed Sister Mary 12 promises that he had made to everyone who venerated and promoted devotion to the Sacred Heart.
He said: “I ask of you that the Friday after the octave of Corpus Christi be set apart for a special feast to honor my heart, by communicating on that day, and making reparation to it by a solemn act, in order to make amends for the indignities which it has received during the time it has been exposed on the altars. I promise you that my heart shall expand itself to shed in abundance the influence of its divine love upon those who shall thus honor it, and cause it to be honored.”
Sister Margaret Mary died in 1690, and Pope Benedict XV canonized her on May 13, 1920.
The Vatican was hesitant to establish a feast to the Sacred Heart of Jesus, but as the devotion grew throughout France, the Vatican granted France the feast in 1765.
Pope Pius IX established the Sacred Heart Feast for the entire Church on the Friday following Corpus Christi in 1856. Since then, the entire month of June is devoted to celebrating the Sacred Heart of Jesus and his unending love for everyone.
The feast of the Sacred Heart of Jesus is not a holy day of obligation, but it is a solemnity on the present calendar, the highest-ranking feast in the liturgical calendar.
St. Margaret Mary Alacoque was given the following promises by the Sacred Heart of Jesus:
1. I will give them all the graces necessary in their state of life.
2. I will establish peace in their homes.
3. I will comfort them in all their afflictions.
4. I will be their secure refuge during life, and above all, in death.
5. I will bestow abundant blessings upon all their undertakings.
6. Sinners will find in My Heart the source and infinite ocean of mercy.
7. Lukewarm souls shall become fervent.
8. Fervent souls shall quickly mount to high perfection.
9. I will bless every place in which an image of My Heart is exposed and honored.
10. I will give to priests the gift of touching the most hardened hearts.
11. Those who shall promote this devotion shall have their names written in My Heart.
12. I promise you in the excessive mercy of My Heart that My all powerful love will grant to all those who receive Holy Communion on the First Fridays in nine consecutive months the grace of final perseverance; they shall not die in My disgrace, nor without receiving their sacraments. My divine Heart shall be their safe refuge in this last moment.