In Eastern traditions, those of the Eastern Catholic and Orthodox Churches, the Divine Liturgy is seen as transcending time, and the world. All believers are believed to be united in worship in the Kingdom of God along with departed Saints and the celestial Angels. To this end, everything in the Liturgy is seen as symbolic, yet also not just merely symbolic, but making the unseen reality manifest. According to Eastern tradition and belief, the Liturgy's roots go back to Jewish worship and the adaptation of Jewish worship by Early Christians. This can be seen in the first parts of the Liturgy termed the "Liturgy of the Catechumens" that includes reading of scriptures and, in some places, sometimes the Sermon/Homily. The latter half was added based on the Last Supper and the first Eucharistic celebrations by Early Christians. Eastern Christians participating in the Liturgy also believe that the Eucharist is the central part of the service, as they believe it truly becomes the real Body and Blood of Christ, and through their partaking of it, they see themselves as together becoming the Body of Christ (that is, the Church). Each Liturgy has its differences from others, but most are very similar to each other with adaptations based on tradition, purpose, culture and theology.
There are three Divine Liturgies in the Byzantine Rite that are in common use:
The Hierarchical Liturgy. As numbers in a diocese increased dramatically the bishop as presiding over the Eucharistic assembly appointed presbyters as celebrant in the local community (the parish). Still, the Church is understood in Eastern Orthodoxy not in terms of the presbyter, but the diocesan bishop. When the latter is present, he is chief celebrant. Phrases and hymns are also added. The hierarch commemorates his hierarch demonstrating unity with the greater Orthodox community.
When not in conjunction with vespers, the liturgies of John Chrysostom and Basil the Great are structured thus:
The format of Divine Liturgy is fixed, although the specific readings and hymns vary with season and feast.
While arrangements may vary from liturgy to liturgy, the Divine Liturgy always consists of three interrelated parts: