Sources for the historicity of Jesus and actions attributed to him. Three of these (Matthew, Mark, and Luke) are known as the synoptic Gospels, from the Greek σύν (syn "together") and ὄψις (opsis "view"), given that they display a high degree of similarity in content, narrative arrangement, language and paragraph structure. The presentation in the fourth canonical gospel, i.e. John, differs from these three in that it has more of a thematic nature rather than a narrative format. Scholars generally agree that it is impossible to find any direct literary relationship between the synoptic gospels and the Gospel of John. The authors of the New Testament
New Testament are most often part of an established lectionary (i.e., selected texts to be read at church services on specific days), and (together with an Old Testament reading and a Psalm) include a non-gospel reading from the New Testament and culminate with a Gospel reading. No readings from the Book of Revelation, however, are included in the standard lectionary of the Eastern Orthodox churches. Central to the Christian liturgy is the celebration of the Eucharist or "Holy Communion". The Words of Institution that begin this rite are drawn directly from 1 Corinthians 11:23–26. In addition, the communal recitation of the Lord's