Santa

After the following discussion, I decided Child #2 wasn't quite ready for "the talk":

Child #2:  Mom, all the kids were talking about Christmas and Santa today at school.
Me:  Oh?
Child #2:  Yup.
Me:  And what were they saying?
Child #2:  They were trying to decide if Santa really exists or not.
Me:  [deep breath] And what do you think?
Child #2:  Doesn't really matter.  I already know the truth.
Me:  You do? 
Child #2:  Yup.
Me: And you're okay with that? 
Child #2:  Yup.
Me:  Do you have any questions?
Child #2:  Nope.  It's just that everyone was wanting to argue with me but I didn't say anything-just listened. But, I know the truth and I'm the only one. 
Me:  [skeptically] And what exactly IS the truth?
Child #2:  Oh, everyone else believes that Santa isn't real.