The document discusses how the Orthodox Christian liturgy is modeled after and draws inspiration from the worship described in the Book of Revelation. It notes that Revelation depicts a "cosmic liturgy" where heaven and earth worship together. Key aspects of the liturgy discussed include lifting worshipers up to heaven, participation in the communion of saints, and the Eucharist representing the marriage feast of the Lamb. The overall theme is that the liturgy allows participation in the heavenly worship and anticipation of the kingdom of God.