Douglas can speak for himself, but it is not the roots, that bother me, it is the fruit of the roots.
The way Halloween is currently celebrated promotes superstition and celebrates indifference to true religion. In a cultural vacuum it is probably defencible, like the Nazis celebrating German folk mythology. In the context of today's culture, it is deplorable. Just like Harry Potter, or Nazi goosstepping in Berlin.
H.L. Mencken defined "Puritanism" as a reaction to the sneaking fear that someone, somewhere was having fun. This silly fear of Halloween and HP is just as indefensible. Let the kids enjoy the night and the Harry Potter books and let the grown ups concentrate on something important.