Posada is Spanish for 'lodging' or 'accommodation'. What you will be witnessing here is the re-enactment of the Christian Nativity. Each house, in the neighbourhood, will schedule a night (between December 16th-24th) to be the posada. Those knocking on the door represent the Biblical Mary and Joseph, seeking somewhere to stay in Bethlehem.
88% of Mexicans are devout Catholics, hence the emphasis on religion at this time of year. Christmas itself is the conflation of the words, Christ Mass. This is celebrated as the anniversary of the birth of Jesus Christ.
The Christian nativity story tells how a census was called in Syria and Judaea, in 6-7CE, which required all of the population to return to their place of birth to be counted. Joseph, a carpenter, had to travel from Galilee to his home city of Bethlehem. With him was his young wife, Mary, who was heavily pregnant. Once there, they discovered that fellow returning ex-pats had filled every hotel, inn, guesthouse and other lodgings for miles around.
Eventually, Joseph begged an inn-keeper for mercy. He pointed to his exhausted wife, who must have been showing the early signs of labour by then. The inn-keeper took pity on the couple, but explained that he really did have no rooms left. He allowed them to rest in his stable instead, along with all of the livestock. The stables were also full, as those travelling to the inn had arrived on horses, donkeys, mules and any other creature that could have conveyed them there.
Joseph found a corner, which he stuffed full of straw, so that Mary could lie down. Shortly afterwards, she gave birth. The baby was Jesus Christ.
Digital art: Matthew Killian
There wasn't exactly a creche attached to the inn, particularly for people bedding down with the livestock. The legend tells how the newborn infant was placed in a manger, as the only available cot. He survived this humble birth to become the central figure of Christianity; the son of God in Catholicism.
It is this story that is the focus of Las Posadas. The community gathers to represent travellers looking for lodgings, at each of the houses in the neighbourhood. They move between them, carrying candles. Four teenagers, amongst the party, will be holding Los Peregrinos (The Travellers). These are large statuettes depicting Mary, on her donkey, and Joseph, leading the donkey. As they knock at each door, none will let them in. They will be told that there's no room inside. Until they reach the house scheduled to hold the event for that night.
As the group move, from house to house, they will be singing a traditional song, entitled 'Villancico Para Pedir Posada'.
The song's lyrics basically tell the story that they are acting out.
When the travellers are finally allowed into a home, they will congregate around the nativity scene prepared there. This is the ceremonial moment, when a figure of the baby Jesus is inserted into the hitherto empty manger. The company will then pray the Rosary before the scene.
Finally, the celebration party begins. This is a joyous occasion, with games for children and a traditional, alcoholic Ponche con Piquete (Punch with sting) for the adults.
When in Mexico this week, look out for Los Posadas. They will be everywhere and they are very beautiful to watch. They are even more wonderful to participate in!