I found the following extracted excerpts in a religious article store. It is called the “Chalking of the Doors.” In many ways it reminds me of the beautiful Jewish custom of the mezuzah.
Above the doors of many homes you may see a mysterious series of letters and numbers, looking for all the world like an equation, inscribed in chalk over a doorway at your parish, or at the home of a friend. Maybe you thought you could figure it out. Maybe you were too embarrassed to ask, “What is that?”
If you don’t know what the chalk is all about, don’t be ashamed. You’re certainly not alone.
Epiphany (also known as the “Twelfth Night”) marks the occasion of a time-honored Christian tradition of “chalking the doors.” The formula for the ritual—adapted for 2019—is simple: take chalk of any color and write the following above the entrance of your home: 20 + C + M + B + 19.
The letters have two meanings. First, they represent the initials of the Magi—Gaspar, Melchior and Balthazar—who came to visit Jesus in His first home. They also abbreviate the Latin phrase, “May Christ bless the house.” The “+” signs represent the cross, and the “20” at the beginning and the “19” at the end mark the year. Taken together, this inscription is performed as a request for Christ to bless those homes so marked and that He stay with those who dwell therein throughout the entire year.
The chalking of the doors is a centuries-old practice throughout the world, though it appears to be somewhat less well known in the United States. It is, however, an easy tradition to adopt, and a great practice whereby we dedicate our year to God from its very outset, asking His blessing on our homes and on all who live, work or visit there.
The timing for the chalking of the doors varies somewhat in practice. In some places, it is done on New Year’s Day. More commonly, it is performed on the Feast of the Epiphany—the Twelfth Day of Christmas. Most often the chalking takes place after Epiphany Mass, and can be done at any church, home, or dwelling. Traditionally the blessing is done by either a priest or the father of the family. This blessing can be performed simply just by writing the inscription and offering a short prayer, or more elaborately, including songs, prayers and processions and the sprinkling of holy water.
After many Epiphany Masses, satchels of blessed chalk, incense and holy water are distributed. These can then be brought home and used to perform the ritual in the days following Epiphany. Another common practice is to save a few grains of the Epiphany incense until Easter, so that it can be burned along with the Easter candle.
Practicing traditions like the chalking of the doors helps us to live our faith more concretely and serve as an outward sign of our dedication to Our Lord. The chalking of the doors of a home encourages Christians to dedicate their life at home to God and to others. Seeing the symbols over our doors can help to remind us, while passing in and out on our daily routines, that our homes and all those who dwell there belong to Christ. It also serves as a reminder of the welcoming the kings gave to Jesus. We should strive to be as welcoming to all who come to our beautiful homes to visit.