Christmas. It is all about the Bride, bearing the fruit of the Holy Spirit, being brought by her Bridegroom to his Father’s house.
Not the beginning of the Gospel (John, at least, places that before the creation of the world, and therefore also before the ‘Fall’ of humanity) but the entirety of the Gospel from inception to completion. In a nutshell, or, at least, a manger.
An enacted parable of Jesus and the Church.