So comprehensive was this prayer that the Catholic bishops of France made it the basis for a short popular catechism, Il est grand, le mystère de la foi: prière et foi de l’église catholique (1978; “It Is Great, the Mystery of the Faith: The Prayer and Faith of the Catholic Church”).
Hymns have been significant vehicles of the Christian faith from the earliest days. They have been sung particularly in the daily offices of the Orthodox and Roman Catholic churches, and they have figured prominently in the Sunday worship of many Protestant churches, especially the Lutheran and Methodist. Congregational singing is appropriate to the “bodily” character of Christianity, in both the physical and the social senses of the word, as it permits the members of the Body of Christ to engage “with one heart and one voice” in the worship of God (Romans 15:5–6). Ethics: obeying the truth
Christians acknowledge not only a duty to announce the gospel, profess the faith, and worship God but also to live their entire lives according to God’s will. Being God’s people means following God’s law, which means walking in the way of truth (Psalm 25:4–5; 86:11) and obeying it (Romans 2:8; Galatians 5:7; 1 Peter 1:22; 3 John 3–4). The dual commandment holds good: to love God and to love neighbour (Matthew 22:37–39). To “dwell in love” is to dwell in God, who is both truth and love (1 John).
Historically, Christian ethical teaching has had two biblical foci: the Ten Commandments (Exodus 20:1–17; Deuteronomy 5:6–21) and the Sermon on the Mount (Matthew 5–7). The emphasis on one or the other has varied across time and space. The Decalogue, as the Ten Commandments are sometimes called, remains valid for Christians, although the divine basis grounding the covenant between God and his elect people has been broadened, according to Christian belief, by the redemptive work of Jesus Christ—a move reflected in the shifting of the chief weekly “holy day” from the Sabbath (Exodus 20:8–11; Deuteronomy 6:12–15) to Sunday, the day of the Lord’s Resurrection, when the Christian community gathers to celebrate the new covenant in his blood and the beginning of the new creation. The “second table” of the Law—honouring parents, and rejecting murder, adultery, theft, false witness, and coveting—has been held by Christians to apply universally, the core of a “natural law” extending beyond the community that has received God’s “special revelation.” In this regard, it functions at least to preserve society against the worst ravages of sin until the preaching of the gospel attains its full range and final goal.
In the Sermon on the Mount, Jesus radicalized the Law by, for instance, making anger murderous and lust adulterous (Matthew 5:21–22, 27–28) and calling for his disciples to be “perfect, as your heavenly Father is perfect” (Matthew 5:48). In the Beatitudes (Matthew 5:1–12), the blessings Jesus offered in the Sermon on the Mount, he declared that the qualities and powers of the impending Kingdom of God were available among his followers in such a way that they would bear a distinctive witness to God before the world (Matthew 5:14–16). Christians have believed that taking the “hard way” (Matthew 7:13–14) is possible by virtue of the divine gift of the Holy Spirit (Luke 11:9–13; cf. Matthew 7:7–12).
In the epistles of Paul, the indicatives of gospel and faith serve to ground the imperatives of attitude and behaviour. Following his exposition of God’s saving actions in Christ in the first 11 chapters of the Letter to the Romans, Paul asserts, “I appeal to you therefore, brothers and sisters, by the mercies of God to present your bodies as a living sacrifice, holy and acceptable to God, which is your reasonable service. Do not be conformed to this world [or age] but be transformed by the renewal of your mind, that you may prove what is the will of God, what is good, and acceptable, and perfect” (Romans 12:1–2).
Christian ethical teaching and practice are intrinsic to the community of the faithful and its life. In the early centuries, certain occupations were considered incompatible with becoming a Christian. According to the Apostolic Tradition, brothel-keepers, prostitutes, sculptors, painters, keepers of idols, actors, charioteers, gladiators, soldiers, magicians, astrologers, and diviners could not become Christians. Moral instruction was provided throughout the catechumenate, and many patristic homilies reveal the ethical teaching and exhortation practiced by the preachers in the liturgical assemblies. Medieval catechesis included the Decalogue, the Beatitudes, and the lists of virtues and vices. The administration of sacramental penance on a regular basis served the formation of individual character and conduct.
Much material became codified in ecclesiastical regulations known as canon law. Whereas the earliest Christians could exercise little or no influence on civil rulers, the “conversion of the Empire” under the 4th-century emperors Constantine and Theodosius permitted bishops their say in the personal and political affairs of emperors and in the wider life of society. In Christendom, legal systems claimed foundations in Christian teaching.