They who have been taught to believe ‘In One God the Father Almighty,’ ought also to believe in His Only-begotten Son. For he that denieth the Son, the same hath not the Father (1Jn 2:23). I am the Door (Jn 10:9), saith Jesus; no one cometh unto the Father but through Me (Jn 14:6). For if thou deny the Door, the knowledge concerning the Father is shut off from thee). No man knoweth the father, save the Son, and he to whomsoever the Son shall reveal Him (Mt 11:27). For if thou deny Him who reveals, thou remainest in ignorance. There is a sentence in the Gospels, saying, (He that believeth not on the Son, shall not see life ; but the wrath of God abideth on him (Jn 3:36). For the Father hath indignation when the Only-begotten Son is set at nought. For it is grievous to a king that merely his soldier should be dishonoured; and when one of his nobler officers or friends is dishonoured, then his anger is greatly increased: but if any should do despite to the king’s only-begotten son himself, who shall appease the father’s indignation on behalf of his only-begotten son? If, therefore, any one wishes to shew piety towards God, let him worship the Son, since otherwise the Father accepts not his service. The Father spake with a loud voice from heaven, saying, This is My beloved Son, in whom I am well pleased (Mt 3:17 ). The Father was well pleased; unless thou also be well pleased in Him, thou hast not life. Be not thou carried away with the Jews when they craftily say, There is one God alone; but with the knowledge that God is One, know that there is also an Only-begotten Son of God. I am not the first to say this, but the Psalmist in the person of the Son saith, The Lord said unto Me, Thou art My Son (Ps 2:7). Heed not therefore what the Jews say, but what the Prophets say. Dost thou wonder that they who stoned and slew the Prophets, set at nought the Prophets’ words? (Saint Cyril of Jerusalem. Catechesis X, no. 1-2)

Whoever is ashamed of me and of my words in this faithless and sinful generation, the Son of Man will be ashamed of when he comes in his Father’s glory with the holy angels. (Mk 8:38)

I am the way and the truth and the life. No one comes to the Father except through me. (Jn 14:6)

And whatever you ask in my name, I will do, so that the Father may be glorified in the Son. If you ask anything of me in my name, I will do it. (Jn 14:13-14)

For there is one God. There is also one mediator between God and the human race, Christ Jesus, himself human. (1Tim 2:5)

Hence, the person and works of Christ are the essential reference point for the faith and prayer life of the people of God. In him we find the Teacher of truth (cf. Mt 22: 16), the faithful Witness (Ap 1:5), the High Priest (cf. Heb 4: 14), the Pastor of our souls (cf. 1 Pet 2: 25), and the one, perfect Mediator (cf. 1 Tim 2: 5; Heb 8: 6; 9:15; 12:24). Through him, man comes to God (cf. Jn 14: 6), the Church’s praise and supplication rise up to God, and all of divine gifts are given to man. (Congregation for Divine Worship and the Discipline of the Sacraments. Directory on popular piety and the liturgy, no. 77, December 2001)

Prayer directed to God must be linked with Christ, the Lord of all, the one Mediator through whom alone we have access to God He unites to himself the whole human community in such a way that there is an intimate bond between the prayer of Christ and the prayer of all humanity. In Christ and in Christ alone human worship of God receives its redemptive value and attains its goal. […] The excellence of Christian prayer lies in its sharing in the reverent love of the only-begotten Son for the Father and in the prayer that the Son put into words in his earthly life and that still continues without ceasing in the name of the whole human race and for its salvation, throughout the universal Church and in all its members. (Congregation for Divine Worship and the Discipline of the Sacraments. The Liturgy of the Hours or the Divine Office, no. 6-7, November 1, 1970)

Christian prayer is characterized by the title ‘Lord’, whether in the invitation to prayer (‘The Lord be with you’), its conclusion (‘through Christ our Lord’) or the exclamation full of trust and hope: Maranatha (‘Our Lord, come!’) or Maranatha (‘Come, Lord!’) – ‘Amen Come Lord Jesus!’ (1 Cor 16:22; Rev 22:20.) (Catechism of the Catholic Church, no. 451)

An essential part of the Church’s work of evangelization is to teach men and women to pray to the Father, through the Son in the Holy Spirit. (Congregation for the Clergy. The priest and the Third Christian Millennium, Teacher of the Word, Minister of the Sacraments, and Leader of the Community, Ch. 3, no. 2 , March 19, 1999)

His training in holiness calls for a Christian life distinguished above all in the art of prayer. […] ‘Lord, teach us to pray!’ (Lk 11:1). Prayer develops that conversation with Christ which makes us his intimate friends: ‘Abide in me and I in you’ (Jn 15:4). This reciprocity is the very substance and soul of the Christian life, and the condition of all true pastoral life. Wrought in us by the Holy Spirit, this reciprocity opens us, through Christ and in Christ, to contemplation of the Father’s face. Learning this Trinitarian shape of Christian prayer and living it fully, above all in the liturgy, the summit and source of the Church’s life, but also in personal experience, is the secret of a truly vital Christianity, which has no reason to fear the future, because it returns continually to the sources and finds in them new life. (John Paul II. Apostolic Letter Novo Millennio ineunte, no. 32, January 6, 2001)

Christ is the one Savior of all, the only one able to reveal God and lead to God. […] No one, therefore, can enter into communion with God except through Christ, by the working of the Holy Spirit. Christ’s one, universal mediation, far from being an obstacle on the journey toward God, is the way established by God himself, a fact of which Christ is fully aware. Although participated forms of mediation of different kinds and degrees are not excluded, they acquire meaning and value only from Christ’s own mediation, and they cannot be understood as parallel or complementary to his. (John Paul II. Encyclical Redemptoris missio, no. 5, December 7, 1990)

Another plan for a continent-wide Synod will concern Asia, where the issue of the encounter of Christianity with ancient local cultures and religions is a pressing one. This is a great challenge for evangelization, since religious systems such as Buddhism or Hinduism have a clearly soteriological character. There is also an urgent need for a Synod on the occasion of the Great Jubilee in order to illustrate and explain more fully the truth that Christ is the one Mediator between God and man and the sole Redeemer of the world, to be clearly distinguished from the founders of other great religions. (John Paul II. Apostolic Letter Tertio millennio adveniente, no. 38, November 10, 1994)

The priest continues to do down the course of the ages, that which Christ Himself had done, who ‘in the days of His earthly life, with a loud cry and tears, offered up prayers and supplications. . . and was heard because of His reverent submission’ (Heb 13:7). This prayer has, without doubt, a singular efficacy because it is done in the name of Christ, ‘through our Lord Jesus Christ,’ who is our Mediator with the Father, presenting to Him incessantly, His own satisfaction, His merits, and the infinite price of His Blood. It is truly ‘the voice of Christ,’ who ‘prays for us as our Priest, prays among us as our Head’ (S. Aug., Ennar. in Ps. 95, n. 1). (Pius XII. Apostolic Exhortation Menti nostrae, no. 39, September 23, 1950)

The Gospel of this Sunday, the Fifth of Easter, proposes a twofold commandment of faith: to believe in God and to believe in Jesus. In fact, the Lord said to his disciples: ‘Believe in God, believe also in me’ (Jn 14:1). They are not two separate acts but one single act of faith, full adherence to salvation wrought by God the Father through his Only-begotten Son.
The New Testament puts an end to the Father’s invisibility. God has shown his face, as Jesus’ answer to the Apostle Philip confirms: ‘He who has seen me has seen the Father’ (Jn 14:9). With his Incarnation, death and Resurrection, the Son of God has freed us from the slavery of sin to give us the freedom of the children of God and he has shown us the face of God, which is love: God can be seen, he is visible in Christ. […] Therefore, only by believing in Christ, by remaining united to him, may the disciples, among whom we too are, continue their permanent action in history: ‘Truly, truly, I say to you,” says the Lord, “he who believes in me will also do the works that I do’ (Jn 14:12). (Benedict XVI. Regina Coeli, May 22, 2011)

This, then, is the salvation of Christians, that, believing in the Trinity, that is, in Father, Son, and Holy Spirit, (and) baptized in it, we must believe without doubt that to it belongs the one and only true Godhead and might, majesty and substance. (Denzinger-Hünermann 177. Synod of Rome, Trinity and Incarnation of the Word, 382 AD)

There is but one Mediator as we know from the words of the apostle, ‘for there is one God and one mediator of God and men, the man Christ Jesus, who gave himself a redemption for all’. (Tim 2:5-6) (Vatican Council II. Dogmatic Constitution Lumen gentium, no. 60, November 21, 1964)

The office of a mediator is to join together and unite those between whom he mediates: for extremes are united in the mean [medio]. Now to unite men to God perfectively belongs to Christ, through Whom men are reconciled to God, according to 2 Corinthians 5:19: ‘God was in Christ reconciling the world to Himself.’ And, consequently, Christ alone is the perfect Mediator of God and men, inasmuch as, by His death, He reconciled the human race to God. Hence the Apostle, after saying, ‘Mediator of God and man, the man Christ Jesus,’ added: ‘Who gave Himself a redemption for all.’ (Saint Thomas Aquinas. Summa Theologica, III, q. 26, a. 1)

Before the whole world let all Christians confess their faith in the triune God, one and three in the incarnate Son of God, our Redeemer and Lord. United in their efforts, and with mutual respect, let them bear witness to our common hope which does not play us false. (Vatican Council II. Decree Unitatis redintegratio, no. 12, November 21, 1964)

‘So everyone who acknowledges me before men, I also will acknowledge before my Father who is in heaven; but whoever denies me before men, I also will deny before my Father who is in heaven’ (Mt 10:32-33). He not only requires faith which is of the mind, but confession which is by the mouth, that He may exalt us higher, and raise us to a more open utterance, and a larger measure of love. For this is spoken not to the Apostles only, but to all; He gives strength not to them only, but to their disciples. And he that observes this precept will not only teach with free utterance, but will easily convince all; for the observance of this command drew many to the Apostles. (Saint John Chrysostom, cited by Saint Thomas Aquinas. Catena Aurea in Mt 10: 32-33)

Since the depravity and iniquity of certain men have reached such a point in our time that, of those who wander and deviate from the Catholic faith, very many indeed not only presume to profess different heresies but also to deny the foundations of the faith itself, and by their example lead many away to the destruction of their souls, we, in accord with our pastoral office and charity, desiring, in so far as we are able with God, to call such men away from so grave and destructive an error, and with paternal severity to warn the rest, lest they fall into such impiety, [desiring to] warn all those and each individually who have up until now asserted, taught, or believed that the almighty God is not three in Persons and entirely simple and undivided in the unity of substance and one in the unique simple essence of divinity, or that our Lord is not true God and of the same substance in every way with the Father and the Holy Spirit; […] We demand and warn on behalf of the Almighty God, Father, Son, and Holy Spirit, and by apostolic authority. (Denzinger-Hünermann 1880. Paul IV, Constitution Cum Quorumdam hominum, August 7, 1555)

If anyone thinks well of the Father and the Son, but does not rightly esteem the Holy Spirit, he is a heretic, because all heretics who think erroneously about the Son [of God I and the [Holy] Spirit are found in the perfidy of the Jews and the pagans. But if anyone divides, saying that God [Christ’s] Father, and God His Son, and God the Holy Spirit are gods, and does not thus say God on account of the one divinity and power which we believe and know (to be) the Father’s, and the Son’s, and the Holy Spirit’s, but taking away the Son or the Holy Spirit, thus believes that the Father alone is called God, or in this manner believes God one, he is a heretic in every respect, nay rather a Jew, because the name of gods was attached and given both to angels and to all the saints from God, but of the Father, and of the Son, and of the Holy Spirit because of their one and equal divinity, not the name of gods, but of God is declared and revealed to us, in order that we may believe, because we are baptized only in the Father, and the Son, and the Holy Spirit and not in the names of archangels or angels, as heretics, or Jews, or even demented pagans. (Denzinger-Hünermann 175-176. Synod of Rome, The Trinity and the Incarnation, 382 AD)

Whoever, therefore, have adverse and contrary opinions the Church disapproves and anathematizes and declares to be foreign to the Christian body which is the Church. Hence it condemns Sabellius who confuses the persons and completely takes away their real distinction. It condemns the Arians, the Eunomians, the Macedonians who say that only the Father is the true God, but put the Son and the Holy Spirit in the order of creatures. It condemns also any others whatsoever who place grades or inequality in the Trinity.
Most strongly it believes, professes, and declares that the one true God, Father and Son and Holy Spirit, is the creator of all things visible and invisible, who, when He wished, out of His goodness created all creatures, spiritual as well as corporal; good indeed, since they were made by the highest good, but changeable, since they were made from nothing, and it asserts that nature is not evil, since all nature, in so far as it is nature, is good. (Denzinger-Hünermann 1332-1333. Council of Florence. Bull Cantate Domino, February 4, 1442)

If anyone does not confess that the Father, and the Son, and the Holy Spirit (are) three persons of one substance, and virtue, and power) just as the Catholic and apostolic Church teaches, but says there is only one and a solitary person, so that He Himself is the Father who is the Son, and also He Himself is the Paraclete, the Spirit, just as Sabellius and Priscillian have asserted, let him be anathema. (Denzinger-Hünermann 451. Council of Braga I. May 1, 561)

If anyone does not confess properly and truly in accord with the holy Fathers that the Father, and the Son, and the Holy Spirit [are a] Trinity in unity, and a unity in Trinity, that is, one God in three subsistences, consubstantial and of equal glory, one and the same Godhead, nature, substance, virtue, power, kingdom, authority, will, operation of the three, uncreated, without beginning, incomprehensible, immutable, creator and protector of all things, let him be condemned. (Denzinger-Hünermann 501.The Lateran Synod 649 AD, Canons condemning errors on the Trinity, can.1, October 31, 649)

For, if we are asked concerning the individual persons, we must confess that each is God. Therefore, we say that the Father is God, the Son is God, and the Holy Spirit is God each singly; yet there are not three Gods, but there is one God. […] Therefore, this Holy Trinity, which is the one and true God. (Denzinger-Hünermann 529-530. Synod of Toledo XI. Creed of Faith, November 7, 675 AD)

If anyone does not confess that Jesus Christ, our Lord, who was crucified in the flesh is true God, and Lord of glory, and one of the Holy Trinity, let such a one be anathema. (Denzinger-Hünermann 432. Council of Constantinople, II Ecumenical V, May 10, 553)

And with the same yearning Our soul goes out to those whom the foul breath of irreligion has not entirely corrupted, and who at least seek to have the true God, the Creator of Heaven and earth, as their Father. Let such as these take counsel with themselves, and realize that they can in no wise be counted among the children of God, unless they take Christ Jesus as their Brother, and at the same time the Church as their mother. (Leo XIII. Encyclical Satis cognitum, no. 16, June 29, 1896)

For a Christian, believing in God cannot be separated from believing in the One he sent, his ‘beloved Son’, in whom the Father is ‘well pleased’; God tells us to listen to him (Mk 1:11; cf. 9:7). The Lord himself said to his disciples: ‘Believe in God, believe also in me’ (Jn 14:1). We can believe in Jesus Christ because he is himself God, the Word made flesh: ‘No one has ever seen God; the only Son, who is in the bosom of the Father, he has made him known’ (Jn 1:18). Because he ‘has seen the Father’, Jesus Christ is the only one who knows him and can reveal him (Jn 6:46; cf. Mt 11:27). (Catechism of the Catholic Church, no. 151)

The opening words of the ‘Creed’ are: ‘I believe in God’. It is a fundamental affirmation, seemingly simple in its essence, but it opens on to the infinite world of the relationship with the Lord and with his mystery. Believing in God entails adherence to him, the acceptance of his word and joyful obedience to his revelation. (Benedict XVI. General Audience, January 23, 2013)

Believing in God means giving up our own prejudices and accepting the actual face in which he revealed himself: Jesus of Nazareth the man. And this process also leads to recognizing him and to serving him in others. (Benedict XVI. Angelus, February 3, 2013)

‘The Catholic Church is alone in keeping the true worship. This is the fount of truth, this the house of Faith, this the temple of God: if any man enter not here, or if any man go forth from it, he is a stranger to the hope of life and salvation. Let none delude himself with obstinate wrangling. For life and salvation are here concerned, which will be lost and entirely destroyed, unless their interests are carefully and assiduously kept in mind.’ (Divin. Instit. IV, 30. 11-12) (Pius XI. Encyclical Mortalium animos, no. 17, January 6, 1928)

With the admonition of the apostle that ‘there is one God, one faith, one baptism’ (Eph 4:5) may those fear who contrive the notion that the safe harbor of salvation is open to persons of any religion whatever. They should consider the testimony of Christ Himself that ‘those who are not with Christ are against Him’ (Lk 11:23), and that they disperse unhappily who do not gather with Him. Therefore ‘without a doubt, they will perish forever, unless they hold the Catholic faith whole and inviolate’ (Symbol .s. Athanasius). (Gregory XVI. Encyclical Mirari vos, no. 13, August 15, 1832)

According to the doctrine contained in the Constitution Dei Verbum, the Christian faith is a conscious and free response of man to God’s self-revelation, which reached its fullness in Jesus Christ. By what Paul calls ‘the obedience of faith’ (cf. Rom 16:26; 1. 5, 2Cor 10: 5-6) the entire man abandons himself to God, accepting as truth what is contained in the word of divine revelation. (John Paul II. General Audience, no. 1, June 19, 1985)

It is impossible for the most true God, who is Truth Itself, the best, the wisest Provider, and the Rewarder of good men, to approve all sects who profess false teachings which are often inconsistent with one another and contradictory, and to confer eternal rewards on their members. […] by divine faith we hold one Lord, one faith, one baptism, and that no other name under heaven is given to men except the name of Jesus Christ of Nazareth in which we must be saved. This is why we profess that there is no salvation outside the Church. (Leo XII. Encyclical Ubi Primum, no. 14, May 5, 1824)

For this reason, the distinction between theological faith and belief in the other religions, must be firmly held. […] This distinction is not always borne in mind in current theological reflection. Thus, theological faith (the acceptance of the truth revealed by the One and Triune God) is often identified with belief in other religions, which is religious experience still in search of the absolute truth and still lacking assent to God who reveals himself. This is one of the reasons why the differences between Christianity and the other religions tend to be reduced at times to the point of disappearance. (Congregation for the Doctrine of the Faith. Declaration Dominus Iesus, no. 7, August 6, 2000)

The Church’s constant missionary proclamation is endangered today by relativistic theories which seek to justify religious pluralism, not only de facto but also de iure (or in principle). As a consequence, it is held that certain truths have been superseded; for example, the definitive and complete character of the revelation of Jesus Christ, the nature of Christian faith as compared with that of belief in other religions, […] the unicity and salvific universality of the mystery of Jesus Christ, the universal salvific mediation of the Church, […] On the basis of such presuppositions, which may evince different nuances, certain theological proposals are developed — at times presented as assertions, and at times as hypotheses — in which Christian revelation and the mystery of Jesus Christ and the Church lose their character of absolute truth and salvific universality, or at least shadows of doubt and uncertainty are cast upon them. (Congregation for the Doctrine of the Faith. Declaration Dominus Iesus, no. 4, August 6, 2000)

For thus shall we raise our thoughts higher than the Jews, who admit indeed by their doctrines that there is One God, (for what if they often denied even this by their idolatries?); but that He is also the Father of our Lord Jesus Christ, they admit not; being of a contrary mind to their own Prophets, who in the Divine Scriptures affirm, ‘the Lord said unto me, Thou art My Son, this day have I begotten thee’ (Ps 2:7). And to this day they ‘rage and gather themselves together against the Lord’ (Ps 2:2), and against His Anointed, thinking that it is possible to be made friends of the Father apart from devotion towards the Son, being ignorant that no man cometh unto the Father but by the Son (Jn 14:6), who saith, I am the Door, and I am the Way. He therefore that refuseth the Way which leadeth to the Father, and he that denieth the Door, how shall he be deemed worthy of entrance unto God? (Saint Cyril of Jerusalem. Catechesis VII – The Father, no. 2)

‘To Abraham were the promises made and to his seed. He says not and to seeds, as if in many, but as it in one, and to your seed which is Christ (Gal 3:16)’ (Leo the Great. To Flavian regarding Eutyches, Letter 28, II, 451 AD)

And if you be Christ’s then are you the seed of Abraham (Gal 4:29). If we therefore because of faith in Christ are deemed children of Abraham, the Jews therefore because of their perfidy have ceased to be his seed. (Gregory the Great. Homily XX, 4^th Sunday of Advent in the Basilica of St. John the Baptist: PL 76, 1164. The Sunday Sermons of the Great Fathers form the First Sunday of Advent to Quinquagesima, London-Chicago, Longmans Green, 1964, vol. I, p. 92)

Who is the liar? Whoever denies that Jesus is the Christ. Whoever denies the Father and the Son, this is the antichrist. No one who denies the Son has the Father, but whoever confesses the Son has the Father as well. (1 Jn 2: 22-23)

Whoever possesses the Son has life; whoever does not possess the Son of God does not have life. (1 Jn 5:12)

If we do not want to act habitually according to the Spirit of Christ, neither can we pray habitually in his name. (Catechism of the Catholic Church, no. 2725)