Moravians are unique in that their churches are decorated, not just with a cross, but with the multi-pointed Moravian star in the chapel, as within the round window here. According to the official Moravian web site's frequently asked questions:
"Whatever its form, the star reminds us of God, who caused the light to shine out of darkness and of the light which is the life of humanity. It reminds us of the promise of Abraham that his descendants would be more numerous than the stars; we are reminded of the star that pointed to the 'great and heavenly light from Bethlehem's manger shining bright.' The Light shines in the darkness, and the darkness has not overcome it. This is the message of the Advent star, which also points to Jesus, who said, 'I am the bright and Morning Star.' It is the star of promise, the star of fulfillment, and the star of hope."
For almost all Christian denominations, Advent, the season before Christmas, begins the liturgical year, representing a season of hopeful waiting for the promise, aka Jesus. (The liturgical year then proceeds through Jesus's life to his Easter Resurrection, after which is what is a long period of what is called "ordinary time," the period without a special emphasis dedicated to Christian teachings which culminates in "Christ the King Sunday" of the "Feast of Christ the King" the Sunday before Advent.) However, everything begins with the miracle of the Incarnation and Christmas.