Santa means saint
and Claus is a last name of Saint Nicholas,
so yes I believe in Santa Claus, he was a very real man that lived a life so filled with the love of God that it touched the lives of other in miracles even after his death.
I guess the next question should be who do the children of atheists believe in and from what source do they find the power to do godly things.
I would guess that the children of atheists don’t really concern themselves with godly things.