BonoVoxSupastar said:
Then tell them the truth, that he doesn't exist.
Actually the story of Santa Claus is based on the life of a real person, a saint named Saint Nicholas. The Dutch veneration of 'Sinter Klaus' was brought to North America with the Dutch settlers and eventually became the story of Santa Claus that everyone knows.
Saint Nicholas was the bishop of a city named Myra in Turkey in the early part of the fourth century. His feast day is December 6th because he died on December 6 or 7 in the middle of the fourth century. Nicholas was first a monk in the monastery of Holy Zion near Myra. Eventually he was made Abbot by the Archbishop, its founder. When the See of Myra, the capital of Lycia, fell vacant, St. Nicholas was appointed its Archbishop. It is said that he suffered for the Faith under Diocletian, and that he was present at the Council of Nice as an opponent of Arianism. His death occurred at Myra, in the year 342.
The most famous story told about St. Nicholas has to do with three young sisters who were very poor. Their parents were so poor that they did not have enough money for the daughters to get married. Every young girl needed money to pay for the wedding and to set up house for themselves. Nicholas heard about this family and wanted to help them, but he did not want anyone to know that he was the one who was helping them.
The story is told in a few different ways. In one version, he climbed up on their roof three nights in a row and threw gold coins down their chimney so that they would land in the girls' stockings, which had been hung by the fire to dry. After two of his daughters had been able to marry because of the money mysteriously appearing in their stockings, the father was determined to find out who was helping them, so he hid behind the chimney the next night. Along came Bishop Nicholas with another bag of money.
When he was discovered, he asked the father not to tell anyone else, but the father wanted everyone to know what a good and generous man the Bishop Nicholas was, so he told everyone he knew. That is how we have the story and the tradition of stocking full of gifts today.
The characteristic virtue of St. Nicholas appears to have been his love and charity for the poor. Because of this and of the many legends of his works, St. Nicholas is regarded as the special patron of children. The Emperor Justinian built a church in his honor at Constantinople in the suburb of Blacharnae, about the year 340.
He has always been honored with great veneration in the Latin and Greek Churches. The Russian Church seems to honor him more than any other saint after the Apostles.
As for why he wears the red Santa suit in our American drawings, well that's the beauty of legends and cultural folklore. It's pervasive and diverse. In anycase, the spirit of Christmas is goodwill and generosity towards your fellow man (and women) and those things transcend all cultural barriers.