It is during the month of November that the Church meditates on the Communion of Saints, which is the link with the faithful who have already reached heaven (the Church Triumphant), the faithful departed who are still expiating their sins in Purgatory (the Church Suffering) and of the pilgrim faithful still here on earth (the Church Militant). As Pope St. Paul VI describes it in his Credo of the People of God: We believe in the communion of all the faithful of Christ, those who are pilgrims on earth, the dead who are being purified, and the blessed in heaven, all together forming one Church; and we believe that in this communion, the merciful love of God and his saints is always [attentive] to our prayers (CCC, 962).
On the 1st of November, The Church celebrates the Solemnity of All Saints, honoring all those faithful in heaven, the known and unknown saints. November 2nd is the Commemoration of All the Faithful Departed (All Souls Day), a day set aside to pray for all the dead. All Souls Day shifts the Church’s focus on praying for the Faithful Departed throughout November. The need and duty of prayer for the dead has been acknowledged by the Church.
It is recommended in the Scriptures of the Old Testament: “It is therefore a holy and pious thought to pray for the dead. Thus, he made atonement for the dead that they be absolved from their sins.” (Macc. 12: 45). This duty is expressed in public and private prayers but especially in the offering of the Holy Sacrifice of the Mass. The prayers are particularly directed for the souls who are being purified in Purgatory, waiting for the day when they will join the saints in Heaven.
The celebration of Mass is the highest means the Church can provide for charity for the dead, but we can also relieve their sufferings through our prayers, our sufferings, and our penances. We can particularly help the Poor Souls by doing acts and prayers that indulgences attached to them.