The ninth article of the Apostles’ Creed is: “[I believe in] the holy Catholic Church, the communion of saints.” We can explore the mystery of the Church as we explore the mysteries of the incarnation and redemption, by asking the six basic questions: what? why? how? who? when? where?

What? Why? How?

What is the Church? According to the Baltimore Catechism, “the Church is the congregation of all baptized persons united in the same true faith, the same sacrifice, and the same sacraments, under the authority of the Sovereign Pontiff and the bishops in communion with him.” In brief, the Church is the Mystical Body of Christ.

In the Mystical Body, Jesus Christ is the head. The faithful are the members. Our Lady is the neck which connects the head and its members. The soul of the Church is the Holy Spirit, and the life of the Church is grace.

Why did Jesus founded the Church? Jesus founded the Church to bring all people to eternal salvation. Indeed, “salvation” is the reason for all three mysteries: Incarnation, Redemption, and the Church. The Church is the continuation of the mystery of the Incarnation, and the Church distributes the fruits of Redemption to all mankind until the end of the world.

How does the Church lead all people to salvation? The Church is enabled by the indwelling Holy Spirit to teach all nations, to govern the faithful, and to sanctify (to administer the sacraments and to offer sacrifice). The Church continues the works of Christ on earth.

Who? When? Where?

Who? Jesus Christ is the founder and the head of the Catholic Church. The Church on earth is made up of clergy and faithful.

The word “church” and the word “school” can refer to both building and people. The school as a community of people has teachers and students, and the Church has clergy and faithful. Teachers serve and instruct the students in school, whereas the clergy serve and instruct the faithful in church.

When? and Where? Grace is the life of the Church, and it was given on Good Friday on Calvary or Golgotha. The Holy Spirit is the soul of the Church, and He was given to the Church on Pentecost Sunday in Jerusalem.

The Church will spread to the end the earth and last till the end of time.

Mother and teacher

Three chief attributes or qualities of the Catholic Church are authority, infallibility, and indefectibility.

The Pope and the bishops, as lawful successors of the apostles, have authority from Christ to teach, to sanctify, and to govern the faithful in spiritual matters.

By the special assistance of the Holy Spirit, the Catholic Church cannot err when she teaches or believes a doctrine of faith or morals.

According to the Baltimore Catechism, “the Church teaches infallibly when it defines, through the Pope alone, as the teacher of all Christians, or through the Pope and the bishops, a doctrine of faith or morals to be held by all the faithful.”

Indefectibility means that the Church, as Christ founded it, will last until the end of time. The Church must preserve unchanged all that she has received from her divine Founder: dogmas, morality, sacraments, and social organization.

Father John Hardon, SJ, the author of The Catholic Catechist’s Manual, points out that the Church is both our mother and our teacher. She is our mother because, with Christ Jesus, she gave us birth in the Spirit. She also sustains and nurtures our spiritual life by her sacraments and prayers.

As teacher, the Church nourishes us by the revealed truth of God.

“No one can have God as father who does not have the Church as mother” (St. Cyprian).

宗徒信經內第九項信條是「我信聖而公教會，諸聖相通功」。正如「降生」和「救贖」的奧蹟一樣，我們探討「教會」的奧蹟時可使用六條基本問題：何物、為何、如何、何人、何時、何地？

何物？為何？如何？

教會是什麼？博迪模要理問答解釋：「聖教會是一總受洗信眾，聚在一起，分享同一信仰、同一祭獻、同一聖事，並且直轄於教宗和他互融的主教團。」或者簡單直接來說，聖教會是「基督的奧體」。

在這奧體，耶穌基督是頭，信眾是奧體中的肢體。聖母是頸，把耶穌與信眾連結在一起；此外，聖神是奧體的靈魂，天主聖寵是這奧體的生命。

耶穌為何要創立聖教會？耶穌要祂的教會引領眾人得到永恆的救恩。的確，「救恩」就是「降生」、「救贖」和「教會」三項奧蹟的因由。聖教會延續聖子「降生」的奧蹟，並分施「救贖」的果實給予萬民，直到世界的終結。

聖教會如何把萬民領入救恩之中？天主聖神臨在聖教會內，促使聖教會訓誨萬民、管理教友、聖化信眾（行聖事獻聖祭），繼續基督在世的工作。

何人？何時？何地？

何人？耶穌基督創立了聖教會，是這教會的頭。塵世間的教會，融合了神職人員和信徒。

「教會」和「學校」兩詞都可指建築物或由人組成的團體。「教會」內有神職人員和平信徒，而「學校」則有老師和學生。老師教導和服務學生，神職人員則教導和服務平信徒。

何時？何地？基督在苦難日，於加爾瓦略山蒙難，賺得了聖寵—-聖教會的生命。在五旬節日，天主聖神於耶路撒冷降臨，成為聖教會的靈魂。

聖教會會傳至世界各地並存在至時間終結。

慈母及導師

聖教會擁有三個主要特質：權威性、無誤性和無缺性。

教宗和主教們，作為宗徒們的合法繼任人，擁有主基督授予的訓導、管轄、和聖化的權柄。

藉天主聖神特別的助佑，聖教會在宣示當信道理和道德操守的訓令時，擁有無誤性(不能差錯)。就如博迪模要理手冊聲稱：「教宗以教會總導師身份，獨自或聯同主教們，向普世信徒頒佈當信道理及當守道德時，保有絕對的無誤性。」

無缺性是指教會為基督所創立，屹立不搖，直至世界末日。當中教會保守着一切從主耶穌接受的信條、道德、聖事和組織，不致有任何偏差或背離其使命。

若望.赫頓神父指出：聖教會是我們的慈母及導師。她是慈母，因為她偕同耶穌基督，在聖神內給我們生命；她又用聖事和祈禱，維繫及養育我們的超性生命。作為導師，聖教會用天主啟示的真理，不斷滋養我們。

聖啟廉曾說過：「誰若不看作聖教會為慈母，又怎能把天主看作父親呢？」