It is a custom throughout the Western world to put candles in the window. The tradition dates back to ancient times and developed into religious symbolism over the ages.
Fire has been a crucial element to human survival since ancient times, and the flames of candles placed in a window have long represented the security and warmth of the hearth. In Christianity, candles represent Jesus Christ, whom the Bible refers to as "The Light of the World."
The custom of displaying candles in the window was brought to America by the Irish in the early 19th century. In Ireland, Catholics were being persecuted by the British. They started to put candles in the window during Christmas to secretly signal to priests that it was safe to come in and deliver the sacraments. They honored the strength of their faith by keeping this tradition alive when they arrived in America.
Colonial Americans picked up the tradition of putting candles in the windows from their new Irish neighbors. They used them to announce births and honor dignitaries. People often put candles in the window today to honor those who have died or are away at war.
In Irish tradition, Christians use candles in the window to symbolize to weary travelers, much like Mary and Joseph, that a house is welcome for company. This custom has been passed down generation to generation and is still in practice.
Placing candles in the window can pose a fire hazard. Electric candles have been used as a safe replacement.