We have an "on the cusp" (8 yrs) in this house and a "no idea what the fuss is about" (3 yrs) , The on the cusp was told when he said I think Santa is not real, this
"If you do not believe he does not come and bring you a present, if you want to take the chance and miss out because you don't believe that is your choice" He rapidly decided he believed.
For me it is not up to someone else to tell my children what is and what is not true when it comes to magic and mystery and imagination, children these days have too much whimsy taken from their lives as it is, let them have some whimsy whilst they are still small, they grow up too quickly.