St. Faustina, born Helena Kowalska in 1905, grew up in a poor but devout family in Poland. When she was 20, she entered the Congregation of the Sisters of Our Lady of Mercy, having been rejected from several other convents because she was uneducated and poor. She took the name Sister Faustina. 

Jesus appeared many times to Faustina, asking her to become a secretary of his mercy, and to write down his messages of Divine Mercy in her diary. He also asked her to have an image of the Divine Mercy painted — red and white rays streaming from Jesus’ heart — and to teach people the Divine Mercy novena. 

Even before she died on October 5, 1938, Faustina spread Jesus’ message to her, and many adopted the devotion to Divine Mercy. 

Pope St. John Paul II was greatly influenced by the devotion to Divine Mercy and the work of Sister Faustina. He canonized her on April 30, 2000, and it was widely reported that he called this day “the happiest day of my life.”