During the British persecution, religion was suppressed throughout Ireland and the people had no churches. Priests were known to hide in forests and caves and they would secretly visit homes to say Mass during the night.
Every Irish Catholic family hoped to have a priest come to their home so they could receive sacraments and offer hospitality. When Christmas came around, the Irish families would leave their doors unlocked and would place a lit candle in the window. This was a sort of signal to let any priests who happened to be in the area know they were welcome and to let the candles guide them to the homes during the dark night.
The priest would enter silently through the unlocked door and was welcomed by those who were grateful that their home would be used to worship and celebrate Jesus' birth.
Over time, the British persecutors became suspicious and asked what the lit candles were all about. The faithful Irish explained that they burn the candles and keep the door unlocked so that Mary and Joseph, who searched for a place to stay, could find their way to our homes and be welcomed with open doors and open hearts. The British soldiers thought that it was a harmless superstition and didn't bother suppressing it.
I didn't know the history behind the candle until recently. I just thought that the battery operated candles looked pretty in my windows. Now, they mean much more. I want them to represent John 8:12 - "Then spake Jesus again unto them, saying, I am the light of the world; he that followeth me shall not walk in darkness, but shall have the light of life."
Do you leave a burning candle in your window during Christmas?