I never lied about Santa, I just didn't tell the truth! DC's 1 and 2 believed fervently, but DC3,( great philososopher that he is) , worked it out for himself by about age 6, much to my sadness.
( But that is him. He told a visiting vicar to his infant school that he didn't believe in God, and why! Much to my horror - I witnessed this as I was training to be a TA in the school at the time! Caused much hilarity in the staffroom, I can tell you!)
But once they all knew, they were under strict instructions not tell those that still believed ,the "truth",because it is part of the magic of Christmas.
At school,if children ask me if Santa is real, I say "What do you think?" and if they say "Yes, he's real" I say "Well,there you are then!" and to those that say "No" I say "How do you know?" If it is obvious that they truly know he is not real i.e. they have seen the presents,or been told by Mum etc, I just say "That's OK, you are in on the secret of how it works, but don't spoil it for others,it is up to their parents to tell them."
It is just a Tradition, isn't it. For those of us who are not religious and believe it is Jesus' Birthday, it is just one in a long line of myths and traditions at this time of year...yule log, mistletoe, holly and ivy, even stars and nativity scenes. Do we really want to stop being traditional?
Obviously it is your choice what you tell your children, but I really don't see the harm in it.
Besides, if you don't tell your children Father Christmas/ Santa exists, how do you explain all the Santa stories and films and pictures of him and the reindeer everywhere, and children queuing at "Santa's grotto",and why they can't go??? A lot of Schools have Santa visit with some sort of present for them.
We're having a Polar Express day at the end of term, watching the film and having hot chocolate and marshmallows . I believe,I do,I do, I do!!! 