From Michael Ruse:
DeAnne has background in education and she will present Part 1 to start Volume IV, The Worship and Liturgical Life of the Orthodox Church. There are five main sections to Part 1:
1. Worship and Theology
2. Liturgical Languages
3. Liturgical Ceremonies
4. The Church Calendar
5. Liturgical Cycles and Liturgical Books
There are three types of calendars used for calculating when to observe feast days, weekly fasting, and other liturgical cycles that are used in Orthodox Churches: Gregorian, Julian, and the revised Julian calendar. What do Orthodox Christians do throughout the year? Liturgical cycles run daily, weekly, annually fixed, and annually movable. Other important books that are used in these cycles include the Menaion, Octoechos, and Horologion; these cycles allow us to read through all the Gospels and Psalms weekly and yearly as well as learn about the lives of the saints.
Each of these smaller sections present us with a similar idea. How do we keep certain features of the old and the new in the Orthodox Church? Metropolitan Hilarion presents us with the idea of a “living Tradition of the Church” that flows from the past into the present. But how is it decided? Should a calendar be updated or kept the same? Should Russian or the inheritance of Old Church Slavonic as a sacred language be kept? The Orthodox Church is experienced in these situations since we've dealt with Arianism and controversies about Pascha before. If some new development causes a schism or a rupture between worship and theology, then it is very likely either a bad idea or not a genuine feature of the Church.
Another important consideration when we start Volume IV is the nature of worship and theology. It’s interesting that this interaction is called lex orandi and lex credendi (Latin for the law of praying and the law of believing) because it’s an inescapable part of life that our beliefs will follow our worship. Actions reveal our beliefs. He explains that what we believe – like the Creed – flows out of how we pray, and nothing in the divine services hinders us from prayer.