The document discusses the Catholic belief in the Communion of Saints. It explains that the Communion of Saints includes all members of God's family, whether living on earth, in purgatory, or in heaven. Those on earth are called the Church Militant and strive to become holy. Souls in purgatory are the Church Suffering and are purified before entering heaven. Saints in heaven are the Church Triumphant and are united with God. All members of the Communion of Saints are united in Christ and share in each other's sufferings, blessings, and prayers.