Chalking the door
Chalking the door is a Christian Epiphanytide tradition used to bless one's home. It is normatively in the pattern of four crosses positioned in between the traditional initials of the three wise men, which are surrounded by the first two and last two digits of the current year. The practice of chalking the door originated in medieval Europe, though it has spread throughout worldwide Christendom.
Epiphany
Either on Twelfth Night, the twelfth day of Christmastide and eve of the feast of the Epiphany, or on Epiphany Day itself, many Christians write on their doors or lintels with chalk in a pattern such as " ✝ C ✝ M ✝ B ✝ ". The numbers in this example refer to the calendar year and the crosses to Christ. The letters C, M, and B stand for the traditional names of the biblical Magi, or alternatively for the Latin blessing Christus mansionem benedicat, or IIIK referring to the three kings.Chalking the door is done most commonly on Epiphany Day itself. However, it may be done on any day within the Epiphany season. In some localities, the chalk used to write the Epiphanytide pattern is blessed by a Christian priest or minister on Epiphany Day, then taken home to write the pattern.
The Christian custom of chalking the door has a biblical precedent as the Israelites in the Old Testament marked their doors in order to be saved from death; likewise, the Epiphanytide practice serves to protect Christian homes from evil spirits until the next Epiphany Day, at which time the custom is repeated. Families also perform this act to represent the hospitality of the Holy Family to the Magi ; it thus serves as a house blessing to invite the presence of God in one's home.
In 20th century Poland, the practice of chalking the door continued among believers as another way of asserting their Christian identity, despite the Eastern Bloc's state atheism and anti-religious campaigns.