Jesus, Lateran Archbasilica, Fr. Lawrence, OP.
“At the centre of the main facade of the Lateran Archbasilica is this mosaic of Christ the Saviour blessing the world.” Fr. Lawrence, OP. Flickr.

Listers, all are welcome to come and know more about Jesus Christ and his Church. The following questions present many of the preliminaries of the Catholic faith. Whether you are a devout evangelical or an inquisitive agnostic, these basic questions will help introduce you to Catholicism and the Rite of Christian Initiation of Adults (“RCIA”). An introduction to Catholicism, however, is really an introduction to a person, the person of Jesus Christ. As such, learning about Catholicism, about Jesus Christ, is less like a linear academic pursuit and more like the blossoming of a relationship. Just as you would come to know a friend or a spouse, persons come to know Christ and his Church. The following questions do not exhaust their subjects, but rather introduce the reader to the central mysteries that permeate the Catholic faith. As one goes deeper into the Catholic faith, these foundational concepts will unfold further and help the person come to know Jesus Christ, the person, more and more. Welcome.

1. Who is God?

“God is the Creator of heaven and earth, and of all things.”1 In the fourth century, the Church adopted a Creed that Christians could learn and confess as a united community. Known as the Nicene Creed, it begins:

“I believe in one God, the Father almighty, maker of heaven and earth, of all things visible and invisible.”

Along with being the Creator, we know God to be both one and triune—meaning, there is only one God, but God is also three divine persons who are both distinct and equal: God the Father, God the Son, and God the Holy Spirit.2 The belief that there is one God in three divine persons is called the Trinity, and the Trinity is an essential mystery in the Catholic faith. By “mystery,” the Church means a “truth that we cannot fully understand” as it surpassing our natural intellect.3 For example, all natural analogies fail to grasp the reality of the Trinity. Often times the Trinity is compared to an egg, where the egg is God and the shell, whites, and the yolk are the three persons. The problem here, however, is that it makes the persons of God parts of God, whereas in reality each person is fully God whereas each part of the egg is not fully the egg. Another common analogy is water. The water is God and the three persons are the three forms it can come in: ice, a solid; water, a liquid; and steam, a gas. The analogy of water falls short of the reality of the Trinity, because unlike the water, the persons of the Trinity are not different modes of God. Each divine person is fully God. The Trinity is a truth that though understandable is not fully comprehendible. It is truth handed down to us by Sacred Scripture and Sacred Tradition, and it is a mystery worth our contemplation and adoration. We, the Church, “praise the Holy Trinity by a form of prayer called the Doxology, which has come down to us almost from the time of the Apostles.”4 In the Doxology, we proclaim: “Glory be to the Father, and to the Son, and to the Holy Spirit. As it was in the beginning, is now, and ever shall be, world without end. Amen.”5 Another form of the Doxology is said at the Mass when we proclaim, “Gloria in excelsis Deo” or “Glory to God in the highest…”6

2. Who is Jesus Christ?

The Gospel of St. John proclaims, “For God so loved the world that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God sent the Son into the world, not to condemn the world, but that the world might be saved through him.”7 Jesus Christ, the Son of God, the Second Person of the Most Holy Trinity, was sent by the Father to redeem the world. As St. Paul states in his Epistle to the Romans, “But God shows his love for us in that while we were yet sinners Christ died for us.”8 The Creed recounts:

I believe in one Lord Jesus Christ, the Only Begotten Son of God, born of the Father before all ages. God from God, Light from Light, true God from true God, begotten, not made, consubstantial with the Father; through him all things were made. For us men and for our salvation he came down from heaven, and by the Holy Spirit was incarnate of the Virgin Mary, and became man. For our sake he was crucified under Pontius Pilate, he suffered death and was buried, and rose again on the third day in accordance with the Scriptures. He ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead and his kingdom will have no end.

The beginning of the Creed makes it clear that Jesus Christ, the Second Person of the Blessed Trinity, is God yet distinct from the Father. He is the Son of God but also “God from God, Light from Light, true God from true God, begotten, not made, consubstantial with the Father.” The term consubstantial denotes that Christ is of the same substance, the divine substance, as God the Father. When the Creed says incarnate, it means that the Second Person of the Trinity took on flesh and became truly man. The incarnation is the second great mystery of the Catholic faith. It is the belief that God became man, and that Jesus Christ was both truly God and truly human. He is one person with a divine nature and a human nature. He was not part God and part man but fully both. Catholics call to mind the mysteries of the Trinity and the Incarnation every time they cross themselves. The making of the sign of the Cross reminds us that God became incarnate and died on the Cross, while the words in the name of the Father, the Son, and the Holy Spirit invoke the Blessed Trinity.

3. Who is the Holy Spirit?

The Holy Spirit is the Third Person of the Blessed Trinity. He is also known as the Paraclete—meaning advocate and counselor—because he prompts the hearts of all mankind to come and love God. The Creed, continuing its Trinitarian structure, states:

I believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son, who with the Father and the Son is adored and glorified, who has spoken through the prophets.

The Holy Spirit descended into the world at an event known as Pentecost. Recorded in the second book of the Acts of the Apostles in the New Testament, the Holy Spirit poured forth upon the Apostles and the Blessed Virgin Mary and he empowered them to be disciples of Jesus Christ. For example, St. Peter, the first pope, denied Christ three times while Christ was undergoing his Passion. At Pentecost, however, the same St. Peter who denied Christ—which included denying Christ to a slave girl—stood up, empowered by the Holy Spirit and proclaimed the Gospel and over three thousand persons entered the Church.9 The same Holy Spirit that empowered St. Peter works in the lives of Catholics to enlighten their minds and enkindle their hearts to love and glory of Jesus Christ.

4. What is the Catholic Church?

The Catholic Church is the “Church established by Christ on the foundation of the Apostles, possessing the fullness of the means of salvation which [Christ] has willed.”10 The Early Church—the period from the Apostles to as late as the eighth century—was very clear that only Christ had the authority to start a Church, and only the Church started by Christ contains the fullness of salvation. The term fullness is used because other Christian communities, e.g., Baptists, Lutherans, Anglicans, Evangelicals, etc., do contain truths. They may believe in the Trinity, in the Incarnation, and in the divine inspiration of Holy Scripture, but they do not have the complete fullness of truth. While they hold to certain parts, they also hold to parts that are not true that give rise to conflicts and contradictions that fracture Christian communities. In this, the Catholic Church is not simply one Christian church amongst many, but is rather the Church, the Church established by Jesus Christ. The Creed, given to us by the Early Church, states:

I believe in one, holy, catholic and apostolic Church. I confess one Baptism for the forgiveness of sins and I look forward to the resurrection of the dead and the life of the world to come. Amen.

The attributes of “one, holy, catholic, and apostolic” are known as the four marks of the Church.11 First, before his death on the Cross, Jesus Christ prayed that his Church would be one as he and the Father were one.12 The “oneness” of the true Church, as Christ said in his prayer, is sign of the presence of God. Unity—spiritual, doctrinal, and institutional—is a sign of charity.13 Second, Catholics, deacons, priests, bishops, and even popes fail and are sinners. While all Catholics are called to holiness, the holiness of the Church is due to her founder, Jesus Christ, and the Holy Spirit working through her.14 Third, the Church is catholic, which means “universal.” The Church is universal in two ways: first, the universality of the Church means that it has the fullness of salvation; second, “the Church is catholic because she has been sent out by Christ on a mission to the whole of the human race.”15 Fourth, the Church is apostolic in a threefold sense: first, Jesus Christ founded the Church on the Apostles, especially St. Peter; second, with the Holy Spirit, the Church is apostolic in her faith, as she passes down the faith of the Apostles; and third, the Church is still guided by the successors of the apostles, the bishops, and especially the pope.16

5. What is RCIA?

The Holy Spirit draws all people toward Jesus Christ and his Church. Whether you already have a relationship with Christ and you are seeking his fullness or you really do not come from a religious background, the Church welcomes all people. The method by which people are welcomed is called RCIA, which stands for the Rite of Christian Initiation for Adults. It is a time to ask questions. It is a rite or ritual that welcomes all persons who wish to know more about Jesus Christ and His Church. Modeled after how the Early Christians brought people into the faith, RCIA offers those discerning the Catholic faith a season of consecutive courses and liturgies that slowly draw the person into a fuller and deeper understanding of the mysteries of the Christian life.

6. Why Does RCIA Take so Long?

RCIA cannot be reduced to the mere transference of knowledge. The courses are not academic in the sense that they represent a series of topics that must be studied in order to graduate into Catholicism. RCIA must be primarily a formative process rather than simply an informative one. The stress on formation over information is due the fact RCIA is introducing you to Jesus Christ. Truth cannot be reduced to a concept but is rather a person—the person of Jesus Christ; and, just as it takes time for an individual to be formed in a relationship with a friend or spouse, it takes time to understand the person of Jesus Christ. Moreover, you cannot love that which you do not know. We must come to know Christ in order to love him. As such, we must allow ourselves to be formed by the teachings of Christ, the knowledge of Christ, in order that our hearts may be able to make a true commitment to Jesus Christ.

7. What is Catechesis?

Catechesis literally means “oral instruction.” In the Early Church, the word catechesis “was given to the totality of the Church’s efforts to make disciples, to help men believe that Jesus is the Son of God so that believing they might have life in his name, and to educate and instruct them in this life, thus building up the body of Christ.”17 The goal of catechesis—of the instruction—is nothing less than “communion with Jesus Christ.”18 Catechesis is not aimed at a concept but at a person—the person of Jesus Christ. In fact, “Jesus Christ himself is always the first and law point of reference in catechesis because he is ‘the way and the truth and the life.’”19 The person who teaches catechesis is known as a catechist, the unbaptized person who is undergoing instruction is call the catechumen, and the teachings of the Church are compiled in a work known as the Catechism.

8. What is the Catechism?

The Catechism of the Catholic Church aims “at presenting an organic synthesis of the essential and fundamental contents of Catholic doctrine.”20 The Catechism is drawn from two sources: Sacred Scripture and Sacred Tradition. Sacred Scripture, the Holy Bible, is the “books which contain the truth of God’s Revelation and were composed by human authors inspired by the Holy Spirit.”21 Holy Scripture, however, testifies that Christ did and said much more than what is contained in the Bible. St. John ends his Gospel by saying, “But there are also many other things which Jesus did; were every one of them to be written, I suppose that the world itself could not contain the books that would be written.”22 As such, Sacred Tradition is essential to having the fullness of Christ’s teachings. Sacred Tradition is the oral and written teachings of the Church as passed on by Christ and his Apostles.23 Sacred Scripture and Sacred Tradition come together in the Sacred Deposit of the Christian Faith, and it is the essential elements of this Deposit that are summarized in the Catechism of the Catholic Church.


  1. Baltimore Catechism #3, question, 132. The Baltimore Catechism (“BC”) was the primary Catechism in the United States from approximately 1885 to the mid 1960s. In turn, the Baltimore Catechism drew from the so-called Small Catechism of St. Robert Bellarmine written in A.D. 1614. Today, the primary catechism is the Catechism of the Catholic Church promulgated by St. Pope John Paul II in 1992. The Baltimore Catechism remains a very useful resource for catechetical instruction due to its clarity and brevity. The simple question and answer formula with concise answers makes it ideal for catechetical instruction, especially when set next to the more in depth theological explanations of the new Catechism of the Catholic Church (“Catechism” or “CCC”). The Baltimore Catechism and the Catechism are both readily available online. ↩︎

  2. See BC qq. 182, 186. ↩︎

  3. BC q. 197, 198. ↩︎

  4. BC q. 203. ↩︎

  5. cf. BC q. 204. ↩︎

  6. cf. BC q. 205. ↩︎

  7. John 3:16-17. ↩︎

  8. Romans 5:8. ↩︎

  9. Acts 2:1–31. ↩︎

  10. CCC, Glossary, Catholic Church. ↩︎

  11. CCC n. 811, ff. ↩︎

  12. John 17. ↩︎

  13. CCC n. 813, ff. ↩︎

  14. CCC n. 823, ff. ↩︎

  15. CCC n. 831. ↩︎

  16. CCC n. 857. ↩︎

  17. CCC n. 4. ↩︎

  18. Directory, 55. ↩︎

  19. Directory, 56. ↩︎

  20. CCC n. 11. ↩︎

  21. CCC, Glossary, Bible; cf. CCC 105. ↩︎

  22. St. John 21:25. ↩︎

  23. See CCC n. 74-79. ↩︎