Grace is the life of the Church. In the natural order, blood is circulated in the human body; in the supernatural order, grace is circulated in the Mystical Body of Christ. The sharing of grace among the members of the Mystical Body is called the “Communion of Saints.”

The Baltimore Catechism defines “Communion of Saints” as “the union of the faithful on earth, the blessed in heaven, and the souls in purgatory, with Christ as their Head.”

The Church triumphant

The saints and angels in heaven compose the Church triumphant, because they have gained the crown of victory.

The blessed in heaven can help the faithful on earth and the souls in purgatory by praying for them. The faithful on earth should honour them and pray to them because they are worthy of honour, and as friends of God, they intercede for us.

There are three types of saints honoured by the Church: biblical saints, traditional saints, and ecclesiastical saints.

Biblical saints are the heroic people in the Bible who died before the end of the apostolic age. Examples of biblical saints are St. Joseph, St. John the Baptist, and the apostles.

Traditional saints are holy people who lived after the apostolic age and whom the Church has not officially canonized. Examples of traditional saints are St. Agnes, St. Cecilia, St. Augustine, St. Benedict, and St. Patrick.

According to Father John Hardon, SJ, the author of The Catholic Catechist’s Manual, “The practice of canonization goes back to the late 12th century. Before then, the Church approved the invocation of certain people as saints but without the now extensive process of canonization.”

Ecclesiastical saints are those officially canonized by the Church. The process of canonization includes beatification. Beatification is the Church’s declaration that a person who practised heroic virtue may be venerated locally or by a specific community.

Canonization is the solemn declaration by the Pope that the faithful should universally invoke a person as a saint. Canonization is an act of infallibility.

The Church suffering

The souls in purgatory compose the Church suffering, because they still have to expiate their sins before they can enter heaven.

According to the Baltimore Catechism, “Those are punished for a time in purgatory who die in the state of grace but are guilty of venial sin, or have not fully satisfied for the temporal punishment due to their sins.”

The souls in purgatory are certain that they are saved. They endure the pain of loss (the temporary loss of the vision of God) and the pain of sense. They experience intense suffering for their purification, but they also experience intense joy for the absolute certainty of their eternal salvation.

The faithful on earth can help the souls in purgatory through the Mass, prayers, sacrifices, and good works.

Father Hardon points out that “we can invoke the souls in purgatory and are encouraged to ask them with the confidence of being heard. They understand our needs and are grateful for the prayers and sacrifices we offer on their behalf.”

St. Catherine of Bologna said, “I received many and very great favours from the saints, but still greater favours from the holy souls” in purgatory.

The Church militant

The faithful on earth compose the Church militant, because we have to struggle ceaselessly against the enemies of our salvation. We can help one another by prayer, penance, and charity.

In order to enjoy fully the Communion of Saints, a person must be in the state of sanctifying grace.

“To those who wish to stand (in God’s grace), neither the guardianship of saints nor the defences of angels are wanting,” St. Hilary said.

聖寵是教會的生命，猶如血液在人體內循環 —— 聖寵臨於基督的奧體，循環運行不息。信眾在奧體內共享聖寵，我們稱為「諸聖相通功」。

博迪模要理手冊把「諸聖相通功」定義為：「天上諸聖、塵世信眾，與煉獄靈魂以基督為首的連結共融。」

勝利的教會

天上諸位聖賢，在世賺得永恆的榮冠，現在偕同一總天使，矗立在勝利的光榮中，是為勝利的教會；他們為在塵世的信眾和煉獄的靈魂祈禱。我們仍處於塵世的信眾應該向他們致敬，他們因在世的懿德芳表而堪當我們的敬重；他們珼在又是天主的朋友，我們可請他們在天主台前代禱。

天主教教會尊敬的聖人有三大類: 聖經時代的聖人、傳統的聖人、和被冊封的聖人。

聖經時代的聖人是宗徒時代結束前去世的聖經偉人；如聖若瑟、洗者聖若翰、諸位聖宗徒等。

宗徒時期後早期的教會，也出現一些值得我們效法的人，雖然教會並未把他們宣聖，但傳統上，教會亦推崇他們為聖者；例如聖依搦斯、聖則濟利亞、聖奧斯定、聖本篤及聖伯特利爵。

按耶穌會會士若望.赫頓神父說：「天主教教會很早已批准信眾尊一些義人為聖人，只是還未有宣聖(冊封聖人)的制度。宣聖制度，要在十二世紀末才開始。」

冊封聖人的過程中包括宣佈聖者為「真福」。宣福(冊封真福) 是教會承認聖者在世時修了英豪的德行，並批准信徒對聖者作出地方性或團體性的敬禮。

至於宣聖，是由教宗以「不能錯」的特恩，隆重地宣告普世信徒要尊某聖者為聖人。

受苦的教會

聖教會的一些聖靈魂，要在煉獄中接受煉淨的苦痛，「他們在離世時，靈魂雖沒大罪，卻仍負有小罪，或仍有未完的補贖，遂要承受煉淨之暫苦。」（博迪模要理手冊）」煉獄的靈魂，即使承受着失苦（暫不能得睹美善的天主）和感覺上的痛苦，但他們在苦痛中經歷莫言的喜樂，因為他們確定最後會獲得永恆的救恩。

我們塵世的教會，可以用祈禱、克苦、善功和奉獻彌撒，來幫助煉靈。若望.赫頓神父更指出：「我們可以祈求煉獄中的靈魂；在向他們祈禱時，我們要有信心。他們明白我們的需要，並感激我們為他們所作的祈禱與犧牲。」

聖加大利納.玻羅諾說：「我從聖人們那裡得到很多很大的恩惠，但從煉靈那裡所得到的恩惠則更多！」

戰鬥的教會

塵世間的教會，還要不斷掙扎，抵抗能損害我們得救的敵人。我們可以會祈禱、補贖、和愛德善功，來彼此幫肋。

須知道，信徒們要在天主的寵愛中(即心中沒有大罪)，才能完滿地享有「諸聖相通功」。

聖依拉略說：「那些願意在天主聖寵內站穩的人，一定不會缺乏聖人的監護和天使的守護。」