Though every Mass is a reminder and a celebration of God's love for us, each Mass may have many subordinate themes. Hence it is good pastoral and spiritual practice to have a feast day specifically dedicated to a remembrance and celebration of God's love for us.

In one of his more spiritual writings, the great German Jesuit theologian Karl Rahner suggested that it is impossible properly to teach devotion to the Sacred Heart. Rather, relying on the Church and its teaching, we can only try to approach the mystery of God's love shown unconditionally and irreversibly in the Sacred Heart of Jesus pierced with a soldier's lance, pouring forth water and blood, which symbolize the sacraments of baptism and Eucharist.

Fr Rahner suggests that a way to develop a deep devotion to the Heart of Jesus, would be to recite a brief prayer such as "Heart of Jesus, have mercy on me" especially in the dark moments of life, — those moments that Pope Francis has recently called "empty moments", when God seems absent or even non-existent.