1. We come to know God on earth by reason, revelation, and experience, and one day hope to see Him face to face.

    1. We can learn a certain amount about God and His callings by reason, especially by learning as well from wise people throughout the ages. But, due to the limitations of human reason and language, we also need God to give us His Revelation, and a Church to interpret it. For there are different levels of knowing God; and to advance to higher levels God gives us greater and greater gifts..

      1. To some degree, one can know God by His gift of reason, although even here we are guided by the light of grace. Thus, for example, one could, in principle, arrive at the knowledge of God as one, holy, almighty, omniscient, and providential. As St. Paul says, “Ever since the creation of the world, His invisible attributes of eternal power and divinity have been able to be understood and perceived in what He has made.” Romans 1:20. But this sort of knowledge of God is limited, and usually riddled with errors because of flaws in human thinking. See Rom. 1:21-22; Wis. 13:1-9.

      2. One also comes to know God by an experience of Him in prayer and in a longing for Him, a longing that is expressed in religions throughout time and space. See Vatican II Council, Nostrae Aetate, Declaration on the Relation of the Church to Non-Christian Religions (1965) 2. This knowledge is more mystical that theological, but should be guided by accurate theology lest it go astray and/or become mere feeling. Here human reason is helpful, but experience shows that there are many errors people can fall into. And, in any case, the mystery of God is vastly above our understanding

      3. To increase our understanding of Him, individually and as a people, God reveals Himself to us, especially in Scripture and in the Church, culminating in the revelation through Jesus Christ. “In times past, God spoke to in partial and various ways to our ancestors through the prophets; in these last days, He spoke to us through a Son.” Heb. 1:1-2. Theology is the rational reflection on that revelation.

      4. But the faith is not merely intellectual. It is lived in practice, for we come to know God by acting in accordance with His laws, and thus acting like Him. As the Spirit guides one’s life, one develops what St. Thomas Aquinas called a “con- naturality” with Him. See Summa Theologica Part II-II, question 45, article 2. Jesus said at the Last Supper, “You will be my friends if you do what I command you. I no longer call you slaves, but friends.” John 15:14. Or, as St. John says, “He who loves is born of God and knows God. By this we know that we love

        the children of God, when we love God and obey His commandments.” 1 John 4:7, 5:2.

      5. Finally, the angels and saints in heaven see God as He is. This knowledge is called the beatific vision, and fills the soul with goodness and light to the point where all future evil becomes impossible. See Catechism 1023. “Beloved, we are God’s children now; what we shall be has not yet been revealed. We do know that when it is revealed, we shall be like Him, for we shall see Him as He is.” 1 John 3:2.

    2. Thus on this earth, we can come to a certain amount of knowledge of God and of His callings to our eternal homeland, but this knowledge is limited.

      1. God gave even pagans a knowledge of the good, which is written on every human heart. But, as St. Paul says, no one has been able completely to carry that desire for goodness out in practice. See, e.g., Rom. 1:19-23, 2:12-24, 3:9-20.

      2. The vast majority of people throughout time and space have intuitively understood that they there is a God (or gods) and that they should offer Him (or them) worship. Even it is not practical for a worldly end, this worship is an essential part of human society. As Pope Francis said in his address at Liberty Hall, Philadelphia on September 26, 2015 religious freedom in all walks of life is crucial “[b]ecause the religious reality, the religious dimension, is not a subculture. It is part of the culture of any people and any nation.” Even such an Enlightenment era figure as Benjamin Franklin said, “There is in all men something like a natural principle which inclines them to devotion or worship of some unseen Power.” Articles of Belief and Acts of Religion (1728).

      3. Likewise, the great philosophical traditions of East and West, as well as native religions, have some consistent social ethics, which, while they differ, do indicate fundamental principles, such as justice, honesty, generosity, family, and reverence. See Vatican II Council, Gaudium et Spes 16 (1965.) C.S. Lewis gives a survey of such principles at the end of his book The Abolition of Man. Such things as the 1948 United Nations Declaration on Human Rights likewise summarizes principles that people generally agree on.

      4. However, there are also some crucial disagreements with regard to religion and morals. The monotheistic religions worship one God, while polytheistic religions worship many gods and goddesses. Even within monotheistic religions, Christianity and Judaism believe in notion of a loving but demanding God and call Him Father; Muslims believe in a God is guides human affairs, but would never call Him Father in any sense; the Enlightenment era philosophers believed in a more abstract God, with images such as the Great Watchmaker or Architect, who simply would up the universe and let it go. And there are even some traditions, whether from ancient paganism or modern vague spirituality, that believe in a God or gods who do not seem to care what we do in the moral life. Without any revelation from God, it would be difficult to make one’s way through the thicket of different beliefs.

      5. It is critical to know about human nature and what is right or wrong in order for us to advance toward the good, the true, the beautiful, and the holy. But we often err in our judgments about such things.

        • We sometimes deceive ourselves because of self-interest and laziness. As Benjamin Franklin said in his Autobiography, “The wonderful thing about being a reasonable creature is that one can make or find a reason for anything one has a mind to do.”

        • Other ignorance may be blameless. But even innocent ignorance leads to error and thus damage to human nature, as even innocent ignorance of medicine can lead people to damage the human body. Sin still causes death and destruction, even is a person does not know the law that he is sinning against and is thus not personally guilty of it. See Rom. 5:12-14.

    3. So that we may know Him and His plan of salvation, God reveals Himself to us through writings, but also through a living tradition. This writing is the Bible and the living tradition of the Church is both Sacred Tradition and the Magisterium.

      1. Without this Revelation, we could only know a limited amount about our eternal destiny, about the way and the end of the journey. And even what could be known by human reason would often be confused by the human tendency to error. See St. Thomas Aquinas, Summa Theologica Part I, question 1, article 1; St. Pope John Paul II, Fides et Ratio (1998) 28.

      2. Thus, God has revealed Himself to us through human history. Starting with Abraham, He formed the Chosen People of old to prepare the way for Christ. See Pope Francis, Lumen Fidei (2013) 8-14. And then Jesus Christ came to earth, revealing God more about who God is in Himself, and declaring Himself to be the way, the truth and the life. See, e.g., John 14:5-14; Lumen Fidei 15-18; St. Pope John Paul II, Veritatis Splendor (1993) 2. But these revelations to specific people throughout time and space had to be handed on to others through visible and tangible means.

      3. One of these means, which Catholics and Protestants agree on (as well as Jews for their portion of the Scriptures) is the written word, which we call the Bible. We maintain that the human authors, using their own talents, intelligence, efforts, and the like, were guided by the Holy Spirit to express the truths God wished to convey firmly, faithfully and without error. The written expression of the truth is contained in the Bible. See Vatican II Council, Dei Verbum (1965) 11; Catechism of the Catholic Church 105-107.

      4. However, the words of Scripture are not the only means of teaching. God also provided for a living tradition of the Church that expresses God’s truth through living practices, and in particular the consistent traditions

        that the Church has maintained from the beginning. We call God’s revelation through the traditions and practices handed on from the Church’s early days Sacred Tradition. The list of books in the Bible, the structure of the Mass, and the roles of the hierarchy are examples of things known through this Sacred Tradition. See Dei Verbum 9.

      5. But there are also ambiguities in both the Bible and Sacred Tradition. And so God also gives His Church the authority to interpret authentically what the Bible and Tradition mean, the truths they contain and how God wants us to live. For example, the early Church did so at the Council of Jerusalem, when the Apostles decided that the Jewish ritual laws did not bind Christians, especially those who had never been Jews. See Acts of the Apostles 15. And, for the sake of clarifying matters that would otherwise be ambiguous, God gave the Church through the Pope and the bishops, the successors to the Apostles, the Magisterium, i.e., the ability to define truths of the faith. See Dei Verbum 10; Summa Theologica Part II- II, question 1, article 9. Scripture expresses the truths of God is a flowing literary fashion, and Sacred Tradition through the practices of the early Church. The Magisterium of the Church, which the Pope and the bishops exercise only with great care, expresses the truths is a more systematic, catechetical style. All three sources of truth (The Bible, Sacred Tradition, and the Magisterium) work together with our own efforts to help us understand more about God and our callings. See Dei Verbum 10; Catechism of the Catholic Church 95.

    4. Faith in Revelation and the Church does not eliminate the need for reason, but rather unites with it. Faith and reason should work together to help us advance in the truth. As Pope John Paul II wrote, “Faith and reason are like two wings on which the human spirit rises to the contemplation of the truth.” Fides et Ratio (1998) 1.

      1. Reason can tell us certain things about God, such as His existence, His eternity, and His orderliness. But we can only get so far with reason alone.

        • Thus, we need revelation to guide us to the heights to which we care called, heights that reason cannot bring us to. Reason itself tells us that reason is limited and thus points the way to faith.

      2. Reason also helps us understand our faith more. For, the Church has, in numerous cases, developed her understanding of the faith by joining reason to her reflections Scripture and Tradition. Examples of this sacred unity include our understanding that God is three persons, Father, Son and Holy Spirit, the fact that the Eucharist is the essence of Christ, with the accidents (or physical attributes) of bread and wine, and the fact that a sacrament is a symbol given by Jesus to the Church that confers the specific grace it signifies. See Fides et Ratio 64-74. Such understandings are examples of St. Anselm’s definition of theology, “Faith seeking

        understanding.” See Catechism of the Catholic Church 158.

  2. In speaking about God, we must use human language, but at the same time, know that language is inadequate.

    1. When speaking about God, we use terms derived from human experience. “Since our knowledge of God is limited, our language about Him is equally so. We can name God only by taking creatures as our starting point, and in accordance with our limited human ways of knowing and thinking.” Catechism of the Catholic Church 40.

    2. Building upon the thought of St. Albert the Great, St. Thomas Aquinas, the leading Dominican of the 13th century and possibly of all time, discussed the issue of how our human words apply to both nature and the things of God and heaven. See Summa Theologica I q. 13, articles 5-6.

      1. Sometimes, words have virtually the same meaning in all contexts; this meaning is called univocal. Thus, for example, the terms “two” or “rectangular” mean virtually the same thing always. St. Thomas pointed out that, if words mean the same thing as applied to earth and heaven, we reduce God down to the same level as this world.

      2. Sometimes, words have completely different meanings when applied in different ways; such meanings are called “equivocal.” Thus, for example, the term “bank” means something completely different as applied to a financial institution or the side of a river. If our language about God and earthly things is entirely equivocal, we could know nothing about God, for the words we use about Him would have nothing to do with the things that we understand.

      3. In between these two terms are the notions of analogy and metaphor. In analogies, the same term means something related, but also different in two different contexts. Thus, when we speak of machines, animals, and people as smart, the meaning changes but not completely. Likewise, we sometimes use metaphors, as when calling someone a night owl or a lap

        dog in order to give a more visible image of the concept we are describing.

      4. In a similar fashion, we use analogies and metaphors when speaking of God. Sometimes, when we speak of God, we use terms that are applicable above all else to Him, e.g., just, merciful, holy, wise; such terms can be applicable to us or others as well to the degree that we participate in God’s goodness. Even here, however, we derive our knowledge of these terms first of all from human experience; and we gradually try to elevate our understanding to God. The meaning as applied to us is analogous to that as applied to God.

      5. At other times, we use terms that are primarily true of human beings and apply them to God or heaven by metaphor. Thus, to refer to God a

        “my rock of salvation” or to apply emotions to Him is to use metaphors to try to understand God.

  3. The belief in the Trinity, expressed in Scripture, and defined during the first ecumenical (i.e. universal) councils of the Church, is that there is one God, who is three persons, Father, Son and Holy Spirit; and the Father the Son and the Holy Spirit are all fully God. We are using here human language to guide us to a mystery that is above human experience.

    1. A person is an individual of an intellectual and spiritual nature; basically when we refer to a person we mean who someone is. A nature is the essence of someone or something; basically a nature is what someone or something is. See St. Thomas Aquinas, Summa Theologica I question 28, article 1-3.

      1. In every other context except the Triune God and the Incarnation, each person has one nature; and a nature belongs to only one person.

        • Thus, each human being is a human person who has a human nature. Likewise, an angel is an angelic person with an angelic nature. Each animal has an animal nature, and some of them reflect certain aspects of being persons, but are not persons as we are because they do not have free will, speculative intellect, or a spirit.

        • Each person and each angel has a nature that reflects part of their species, but not all of it. Thus, for example, each person has some of the intellect of the human race, some of its freedom, some of its sense of beauty, but not all of it.

      2. By contrast, with God, the divine nature cannot be broken up into parts, with different people having only a part of it. For example, if one divided omniscience into three parts, each part would only be a third of all knowledge, not the whole. The same would be true of all-holiness, omnipotence, etc.

        • Thus, for a person to have divine nature in the sense of the nature of the Almighty God means that He must have all of it. Otherwise, His nature would not be divine in that sense. The pagans of course refer to gods who divide up power, but that is precisely because they do not believe that any of these gods are the final reality.

      3. God is therefore one. But sharing the one Godhead are three persons, Father, Son, and Holy Spirit who share that one divine nature. See Catechism 253-256.

        • Two humans could not perfectly share a human nature because, being of imperfect intellect and will, they would not always agree on what to do with it. But such limitations do not apply to God. Each divine Person, the Father, the Son and the Holy Spirit is completely in accord the other Persons because they all know the good perfectly and wish the good completely.

      4. Everything that God does and has the three Persons do and have together, except for the Son becoming Man and thus acting, thinking, feeling, praying and the like as a human. What distinguishes them is their relationship with each other.

        • The Father begets the Son; in other words, the Father brings forth a Person with His own nature. We make things beneath us; we beget people at our level. Thus, parents beget their children because children are human beings like they are. But God makes our souls because He is above us.

        • The love between the Father and the Son is so powerful that this divine love is a person, the Holy Spirit. In human relationships, such things as a family, a team, or a school are often said to have a “spirit,” which is connected to individuals but distinct from them; and this spirit is sometimes spoken of as like a person. What is symbolically true in humans is fully and totally true in God. The love between the Father and the Son is another divine person, the Holy Spirit.

      5. Although it is not inconsistent with reason, this doctrine of the Trinity is above reason and is thus known because of revelation. Jesus revealed God as Father, Son and Holy Spirit. See, e.g., Matt. 28:19. The Holy Spirit would guide the Church to understand the meaning of the words of Christ. See, e.g., John 14:25-26, 15:26-27, 16:12-15. Saint Paul also often refers to God, Christ the Lord and the Spirit in the same passages, indicating a certain equality. See, e.g., 1 Cor. 12:4-7; Eph. 2:18-22, 4:4-6, 6:10-20. He did not use the language we do, as three persons sharing one nature, for that language had not yet been developed.

        • Furthermore, we can see in reason why this doctrine of the Trinity is fitting. For, if God were not three persons, then in the end God would love only Himself at His level. He could love others below His level, as we can love animals, a house, or a painting. But we would have an ability that He would not, to love another like ourselves.

        • In revealing that there is a Trinity, Jesus and the Church show that this human love is not merely an emotion on earth, but rather the most perfect reflection of the divine, where each Person loves the other Divine Persons perfectly. As St. John says, “God is love.” 1 John 4:16.

    2. The idea of the Trinity is difficult to understand because this reality of three persons sharing one nature is nowhere else in our experience. But several analogies can perhaps help, although all of them fall short.

      1. One analogy, from St. Augustine’s early fifth century work De Trinitate, is the relationship between the thinker, the act of thinking and a thought. The three intimately related, but distinct.

        • This analogy does have a weakness because the thinker is prior to, and greater than, the thought or the act of thinking.

      2. Another analogy is between the intellect, the free will, and the sense of beauty of each person. The three aspects of human nature are distinct, but inseparable from each other.

        • There is a weakness in this analogy because none of these faculties of the human person is a person; and, in the human person, they can go in different directions.

      3. Another analogy is a husband and wife who join their whole lives together, and produce children of the same nature as themselves. Husband, wife, and children share the family-hood together.

        • There is a weakness here as well because husband, wife and children are different persons, come into being at different times, and have different roles.

      4. A further analogy is a partnership. In American law, each partner presumptively owns all of the assets of the partnership and can make decisions for the entire partnership. As a practical matter, things are often more divided, but in principle, the entirely of the partnership (e.g., law, medicine, business) can reside in each partner, for each one can buy, sell, hire, or act for the entire partnership.

        • There is a weakness here because the partners are different persons who exist separately from, and prior to, the partnership. In addition, the partners usually do different things for the partnership.

      5. According to a common tradition, St. Patrick drew the famous shamrock analogy. The idea is that the shamrock is, at the same time one shamrock and three petals. And each petal is fully a shamrock.

        • There is a weakness here because each petal is not fully a shamrock, and could be separated from the whole. By contrast each person of the Trinity is fully God and inseparable from the others.

    3. Another explanation of the Trinity is based paradoxically upon the ideas of a leading twentieth century Jewish philosopher Martin Buber.

      1. As expressed especially in his 1923 classic I and Thou, we as humans enter into many types of relationships with others. And each of these relationships has a type of spirit to it, hopefully a good one. The ability to enter into these relationships is central our nature and we do not grow as people without a growth in these relationships.

      2. At the height of these relationships is what he calls the I-Thou relationship, which is analogous to the Christian virtue of love. In such a relationship, one sees the other as having a goodness that is central to all of reality. Entering into that highest of all relationships is what fulfills human nature; a human life is less that human without it.

      3. As Dr. Buber goes on to say, when any person has that I-Thou relationship with another, he is (whether he knows it or not) entering into a relationship with the Almighty God. Thus, for example, if a man loves his wife because she is wise or kind or understanding, he is also honoring the source of wisdom, kindness, or understanding, which is God Himself. Or, if a person truly appreciates an aspect of nature because it is beautiful or majestic, he enters into a relationship with beauty or majesty itself, which have their source in God.

      4. The next step goes beyond what Dr. Buber said, but flows from it. God loves us perfectly. And thus, by loving us for our goodness, truth. beauty, and call to holiness He also loves Himself the source of all goodness, truth, beauty and holiness. But this love is not merely a self-love. It is the love of another, through Whom He created all of us. See John 1:3, Col. 1:16. It is the love of His Son, who perfectly shares His love.

      5. As with human relationships, but even more so here, there is a spirit of this love between the Father and the Son. We sometimes describe the spirit of human relationships as almost like a person (e.g., a team spirit, a school spirit, espirit de corps.) In human relationships, the spirit of the relationship is not actually a person, but we use the analogy all the same. But this love of God the Father and God the Son is perfect in all ways and fully divine. And thus this love is a divine person, the Holy Spirit.

  4. Knowledge of this doctrine is central to our lives for several reasons. See article “Trinity”, in Encyclopedia of Catholic Doctrine (Our Sunday Visitor 1997) at 682, 684- 5.

    1. First, it draws us closer to God by enabling us to know more and more about who He really is. One can love another if one knows more about him, and love seeks more accurate knowledge of the other. Thus, if we love God, we will want to know more about Him; and an increasing knowledge of God will help us love Him all the more. .

    2. Knowledge of the Trinity helps us to understand what St. John means when he says that “God is love.” 1 John 4:8, 16. With the understanding of the Trinity, we see that love in at the core of all things. This love, the love of the Father and the Son Who is the Holy Spirit, is before all of creation. And from this love all of creation springs.

    3. Furthermore, knowledge of the Trinity gives us knowledge of ourselves more.

      • It is easy to think that one is a better person if one is more independent of others, and that relying on others makes us less like God.

      • But knowledge of the Trinity indicates that inter-personal relationships make us most like God. Love of others on earth is the closest we come to God other than the love of God Himself; and the two are tied inseparably together as Jesus makes clear when He describes the two greatest commandments as love of God and love of neighbor. See, e.g., Matt.

      22:34-40; Mark 12:28-34.

    4. The Trinity exemplifies how one can have hierarchy without inequality and unity without sameness. The Father begets the Son, and the Holy Spirit proceeds from them. However, even though the Father is first is order (not in time, for the God is outside of time), the three persons are still equal. Likewise, the Church has many different types of people; and in fact each person is unique. And yet, at the same time, she is one throughout all of time and space, and beyond time and space. See John

    5. We also see how perfection can involve both permanence and yet continual action. God is permanent and outside of time, and yet the procession of love among the person is continually active. We see nothing permanent or eternal on earth, and so this fact is difficult to understand. But, for example, when one sees a waterfall flowing, or a clock moving, one can get a sense of a certain image of permanence, and yet also action. John 17:20-23; Romans 12:4-8; 1 Cor. 12:4-31

    6. By reflecting on the persons of the Trinity, all united and yet distinct, understand our relationship with God which is one, but also varied. By the Son, we are adopted sons and daughters of the Father. See, e.g., John 1:12; Gal. 3:26. By the Incarnation, we are joined with God through our human lives. See, e.g., John 17:9-10; Gal. 2:20. And we are also dwelling places of the Holy Spirit; as the Holy Spirit came down upon the prophets, the authors of Scripture and Mary at the Incarnation, the Holy Spirit descends upon us as well. See, e.g., 1 Cor. 3:16, 6:19; 2 Cor. 6:16.

    7. In order to accomplish these effects, the Son became man. And this understanding (to the degree that we can understand it) of the Persons and Nature of God prepares us to see how Jesus Christ can be both God and man. For the Son of God, while always having divine nature from all eternity, took on human nature about 2000 years ago, and is, therefore, fully God and fully man.