CIC 172 Through the centuries, in so many languages, cultures, peoples and nations, the Church has constantly confessed this one faith, received from the one Lord, transmitted by one Baptism, and grounded in the conviction that all people have only one God and Father.1 St. Irenaeus of Lyons, a witness of this faith, declared:

CIC 249 From the beginning, the revealed truth of the Holy Trinity has been at the very root of the Church’s living faith, principally by means of Baptism. It finds its expression in the rule of baptismal faith, formulated in the preaching, catechesis and prayer of the Church. Such formulations are already found in the apostolic writings, such as this salutation taken up in the Eucharistic liturgy: “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.”2

CIC 814 From the beginning, this one Church has been marked by a great diversity which comes from both the variety of God’s gifts and the diversity of those who receive them. Within the unity of the People of God, a multiplicity of peoples and cultures is gathered together. Among the Church’s members, there are different gifts, offices, conditions, and ways of life. “Holding a rightful place in the communion of the Church there are also particular Churches that retain their own traditions.”3 The great richness of such diversity is not opposed to the Church’s unity. Yet sin and the burden of its consequences constantly threaten the gift of unity. And so the Apostle has to exhort Christians to “maintain the unity of the Spirit in the bond of peace.”4

CIC 957 Communion with the saints. “It is not merely by the title of example that we cherish the memory of those in heaven; we seek, rather, that by this devotion to the exercise of fraternal charity the union of the whole Church in the Spirit may be strengthened. Exactly as Christian communion among our fellow pilgrims brings us closer to Christ, so our communion with the saints joins us to Christ, from whom as from its fountain and head issues all grace, and the life of the People of God itself”5:
We worship Christ as God’s Son; we love the martyrs as the Lord’s disciples and imitators, and rightly so because of their matchless devotion towards their king and master. May we also be their companions and fellow disciples!6

CIC 1454 The reception of this sacrament ought to be prepared for by an examination of conscience made in the light of the Word of God. The passages best suited to this can be found in the Ten Commandments, the moral catechesis of the Gospels and the apostolic letters, such as the Sermon on the Mount and the apostolic teachings.7

CIC 2219 Filial respect promotes harmony in all of family life; it also concerns relationships between brothers and sisters. Respect toward parents fills the home with light and warmth. “Grandchildren are the crown of the aged.”8 “With all humility and meekness, with patience, [support] one another in charity.”9

CIC 2790 Grammatically, “our” qualifies a reality common to more than one person. There is only one God, and he is recognized as Father by those who, through faith in his only Son, are reborn of him by water and the Spirit.10 The Church is this new communion of God and men. United with the only Son, who has become “the firstborn among many brethren,” she is in communion with one and the same Father in one and the same Holy Spirit.11 In praying “our” Father, each of the baptized is praying in this communion: “The company of those who believed were of one heart and soul.”12

1 Cf. Eph 4:4-6.
2 2 Cor 13:14; cf. 1 Cor 12:4-6; Eph 4:4-6.
3 LG 13 § 2.
4 Eph 4:3.
5 LG 50; cf. Eph 4:1-6.
6 Martyrium Polycarpi, 17: Apostolic Fathers II/3, 396.
7 Cf. Mt 5-7; Rom 12-15; 1 Cor 12-13; Gal 5; Eph 4-6; etc.
8 Prov 17:6.
9 Eph 4:2.
10 Cf. 1 Jn 5:1; Jn 3:5.
11 Rom 8:29; Cf. Eph 4:4-6.
12 Acts 4:32.