[Divine Mercy in my soul] also known as the Diary of Saint Faustina records Saint Faustina Kolwaska mystical experiences and revelations of Jesus as the Merciful Jesus, the Divine Mercy. She was a Polish nun. There are many themes in the Diary, but the main theme is God's Divine Mercy and trust in Jesus, prayer, and mercy toward others. Her writings included the experiences directly with Jesus. He often told her to “write this down” and dictated the prayers to her and told her to pray it ‘unceasingly’, this was later called the [Chaplet of Divine Mercy].

 Here are some key themes found in The Diary of Saint Faustina:

1. Divine Mercy – God's infinite mercy for all souls, especially sinners.
2. Trust in Jesus – The phrase “Jesus, I trust in You” is central.
3. Suffering and Sacrifice – Offering her own suffering for the salvation of souls.
4. Prayer and Contemplation – Deep devotion through prayer, especially the Divine Mercy Chaplet.
5. Obedience and Humility – Submission to God’s will and spiritual authority.
6. Spiritual Warfare – Encounters with temptation and the devil.
7. Love and Compassion – Acting with mercy toward others.
8. The Eucharist – Reverence for the Holy Communion.
9. Visions and Mystical Experiences – Encounters with Jesus, Mary, and angels.
10. Mission of Mercy – Spreading the message of Divine Mercy to the world.