Patristics: Patristics or patrology is the study of the early Christian writers who are designated Church Fathers. The names derive from the combined forms of Latin pater and Greek patḗr (father). The period is generally considered to run from the end of New Testament times or end of the Apostolic Age (c. AD 100) to either AD 451 (the date of the Council of Chalcedon) or to the Second Council of Nicaea in 787. Liturgy: The term “liturgy” literally in Greek means “work for the people”, but a better translation is “public service” or “public work”, as made clear from the origin of the term as described above. The early Christians adopted the word to describe their principal act of worship, the Sunday service (Holy Eucharist, Holy Communion, Mass or Divine Liturgy). This service, liturgy, or ministry (from the Latin “ministerium”) is a duty for Christians as a priestly people by their baptism into Christ and participation in His high priestly ministry.