When we say, “I believe in the Communion of Saints,” we mean that we believe that there is a union, a fellowship, of all souls in whom the Holy Spirit, the Spirit of Christ, dwells. This communion is the union of the members of the Church on earth, in Heaven, and in Purgatory.
The word “communion” means “union with.” The word “saint” means “holy.” Every Christian soul, incorporated with Christ by Baptism and having within himself the Holy Spirit, is holy so long as he remains in the state of sanctifying grace. In the early Church, all faithful members of the Mystical Body of Christ were called saints.
The Communion of Saints is the unity and cooperation of the members of the Church on earth with those in Heaven and those in Purgatory, all of whom are united in the one Mystical Body of Christ.
The faithful on earth are in communion with each other by professing the same faith, by obeying the same authority, and by assisting each other with prayers and good works. They have communion with the saints in Heaven by honoring them as glorified members of the Church, by invoking their prayers and aid, and by striving to imitate their virtues. They are in communion with the souls in Purgatory by helping them through prayers and good works, especially through the Holy Sacrifice of the Mass.
The Church is not only the family of those living in faith here on earth. It is a Communion of Saints. It reaches into eternity, embracing also all who are being purified to enter the Beatific Vision and all who are already rejoicing in the beholding of God’s glory. Our union with those we love who have gone to sleep in the peace of Christ is not in the least interrupted. Their entrance into life has not ended their union with us. Through their entrance into life, we too are brought nearer to God.
Their blessedness is not yet totally fulfilled, for they await the final resurrection and the sharing of that flesh which is part of their being in the joy of eternal life. They await the Last Judgment with the gathering into total newness of life the full number of all the redeemed. But the source of their beatitude is already theirs. They have come to see and to possess their God in the Beatific Vision.
The blessed not only enjoy the blessedness of God’s immediate presence, the indescribable happiness of knowing and loving God as He knows and loves Himself, but they also contribute to the building of the Kingdom by praying for their brothers and sisters in Christ who are still here on earth. Their happiness is intensified by the realization that they can influence the Salvation of those whom they know and love. They look upon the goodness and share the perfect peace of Christ as they await with joyful longing the final resurrection and final judgment when all will be made perfect in God.