The Truth About Santa Claus?

Someone told my son when he was 5 and i so was not impressed! But my reply to him was that Santa does exist as long as you believe in him, but if you stop believing he'll stop coming and and you will not get presents from him anymore but your parents will buy them instead. He's 8 now and still believes, another child told him again this year and instead of telling me, he wrote a letter directly to Santa telling him that so and so did not believe in him anymore, but can he bring him something anyway, bless him!