There is a tradition of blessing chalk at Epiphany to mark the threshold of our homes with a new year blessing.
It picks up Old Testament traditions of marking the doorposts of the house with biblical texts (Deuteronomy 6:9), the theme of the Holy Family welcoming visitors to their home to visit the Christ-child, and a reminder of the importance of hospitality throughout the Scriptures. Because of the timing of Epiphany at the start of the year, it also offers a chance to pray for God’s blessing at the start of the new year.
The letters and numbers that people chalk on their doors pick up the new year, the Epiphany story, and the prayer for blessing in a simple formula, written like this 20 + C + M + B + 25. The 20 and 25 are of course the beginning and end of the year’s date. The middle three letters stand for the traditional names of the wise men (magi): Caspar, Melchior and Balthasar. They also represent the initials of the Latin phrase “Christus mansionem benedicat” – “Christ bless the house.” Together they represent our prayer at the start of the year that our homes, too, may be places blessed by the love and light of Christ.