What does communion of saints mean?
Communion of saints means the union of the living members of the Church on earth, the blessed members of the Church in heaven and the suffering members of the Church, those who are undergoing final purification of their sins in purgatory, with Jesus, their Head. Taught in the Scriptures, the doctrine of communion of saints is defined by the Magisterium of the Church in this way: “The life of each God’s children is joined in Christ and through Christ in a wonderful way to the life of all the other Christian brethren in the supernatural unity of the Mystical Body of Christ, as in a single mystical person.” (Paul VI, Indulgentiarum Doctrina, no. 5; CCC, no. 1474; For scriptural passages on the doctrine of the communion of saints, see, for instance, Acts 4: 32-37; 1 Cor. 12: 12-27; Col. 1; 1 Jn. 3: 16-18)
In the communion of saints, the threefold members of the Church, help one another and care for one another, so that in the end all of us will be united in Jesus Christ, our Lord in eternal life. What brings us together and supports us, in the communion of saints? Our Catechism teaches that charity and exchange of spiritual goods between members of the Church join all of us in and through Christ.
These spiritual goods which we exchange and which God, the Blessed Virgin Mary and the saints offer to us and to the souls in purgatory refer to the satisfactions and merits of Jesus, the prayers and good works of Mary and the saints, which they merited through Christ when they were still alive. (See CCC, 1474-1477)
What about the souls in hell? Do they belong to the communion of saints?
Obviously, they are not included because they opted to separate themselves from the love of Christ, by their mortal sins. We don’t pray for them because our prayers will not relieve their eternal pain and suffering due to their un-repented and un-forgiven mortal sins. The souls in hell will stay forever in hell until the last judgment, where their bodies will join their souls in the eternal exclusion from communion with God, Mary, the angels and saints.
Grace unites us the members of the Church. Sin breaks ecclesial communion. How do we, the faithful on earth, restore or re-establish communion? The Sacrament of Penance restores us and re-establishes us in the Communion of Saints.
How can we, the faithful on earth, help the souls in purgatory?
We, the pilgrims on earth, can help the suffering members of the Church in purgatory by praying, fasting, good works, offering indulgences and offering Masses for them. The souls in purgatory are assured of heaven. Through our prayers, good works, fasting, offering of indulgences, and Masses for them, their entrance into heaven is hastened. Certainly, only God knows when the souls will finally be relieved from purgatory.
How can the saints in heaven help us and the souls in purgatory?
We, the faithful on earth, pray to the blessed members of the Church in heaven. Now that they are with the Lord, the blessed “intercede unremittingly with the Father on our behalf, offering the merit they acquired on earth through Christ Jesus…” (Indulgentiarum Doctrina, no. 5) We pray for the souls in purgatory but pray to the blessed in heaven, so that they may intercede for us the faithful on earth and for the suffering souls in purgatory.
Can the souls in purgatory help us?
The souls in purgatory, inasmuch as they are members of the communion of saints, can help us by praying for us but they can no longer pray for themselves. Moreover, they can no longer make satisfaction or reparation for their sins. We, the faithful on earth, their relatives, friends, family members pray for them and make reparation for their sins by doing good works, offering indulgences and Masses for them.
How can we help one another here on earth in this communion of saints?
We can help one another attain communion with God by practicing charity and by performing spiritual and corporal works of mercy.
All saints and angels of God, come to our aid. Lead us into life eternal, God's heavenly home.