Depicted is the Holy Trinity according to the Old Testament – the visit of the three angel messengers to Abraham and Sarah in the grove of Mamre. This visit indicates the appearance of the Trinity. The three angels are seated around a table with a goblet on it. Each holds a staff, the symbol of authority, representing the same divine authority.
The visit that Abraham received in Mamre from “three men” – as it is called in the Bible (Gen 18.2) – and which some early church fathers understood as a mysterious reference to the three-person God, is seen by the Eastern Orthodox Church as the interpreted appearance of the Divine Trinity. While the Western Church has celebrated its own Trinity feast (on the first Sunday after Pentecost) since the high Middle Ages, the Eastern Church commemorates the appearance of the three angels to Abraham on Pentecost Sunday as a symbol of the triune God.
Trinity (a being that is threefold or unfolded in its unity), Greek “trias”, Russian “troica”: the fundamental doctrine of Christianity of the unity of the three divine persons God the Father, God the Son and God Holy Spirit. It is common to all Christian denominations and distinguishes Christianity from all other religions. After disputes in the 2nd and 3rd centuries, it was provisionally concluded in the Creed of Nicea in 325 and in the Niceno-Constantinopolitan Creed of 381.