Although Orthodox Christians have at their disposal various institutions of learning such as schools, universities, and seminaries, and do hold “Sunday Schools,” at least in the USA, it is fair to say that the main catechetical vehicle for all Orthodox peoples is the Divine Liturgy. All the liturgical prayers are self-contained: they enshrine the history, the story, the meaning, and the practical application of what is celebrated every Sunday, major feast, and commemoration of angels, saints, and prophets. If one pays attention – and “Be attentive” is a common invitation made throughout the Divine Liturgy – the worshipper catches all that he or she needs to know and live the Orthodox faith without need for further specialized education. For this very reason, the Divine Liturgy, more than any other focus of “power and authority,” is the true locus of Orthodox unity and the principal explanation for Orthodox unity and resiliency throughout history.

From Orrologion