In Christianity, the Nativity Fast is a period of abstinence and penance practiced by the Eastern Orthodox Church and Catholic Church in preparation for the Nativity of Jesus on December 25. The corresponding Western season of preparation for Christmas, which also has been called the Nativity Fast and St. Martin's Lent, has taken the name of Advent. The Eastern fast runs for 40 days instead of four (in the Roman Rite) or six weeks (Ambrosian Rite) and thematically focuses on proclamation and glorification of the Incarnation of God, whereas the Western Advent focuses on the two comings (or "advents") of Jesus Christ: his birth and his Second Coming or "Parousia".