Meri, the point of using Santa Claus to give this message is a reference to a true story involving an 11 year old girl named Virginia.

It was during the late 1800's in America. This young girl asked her father if there really was a Santa Claus. He father instructed her to write the local paper for her answer. Her father said if the editor said he was real then it was so. The now famous letter that virginia received back was beautiful. And the famous line was, "Yes, Virginia...there really is a Santa Claus."

I'm repeating this all from memory, so I probably have a few of the details wrong.