Halloween YES! We are Christians, and we celebrate it enthusiastically. Each year around this time I hand out candy to THOUSANDS (yes, that's right) of kids at a community fund-raiser. On Halloween night itself, I put together gift bags that contain not only treats, but party favors and, this year, some clean Halloween jokes and riddles. I get a real kick out of the kids' reactions. For me, Halloween is a real community-builder. The Christian ideal is to fellowship with others, spread love and joy, and that's what I do.
As for worrying about the ghosts, goblins, evil things, etc., I think Halloween is a valuable lesson in dealing with those fearful things. First, by approaching these things with a lighthearted attitude, you learn that good triumphs over evil. Scary things are not so scary when you laugh at them. Facing your fears is better than denying them. You can take a scary situation, make the best of it, and maybe have some fun.
I don't go for the gross and yucky stuff, but I have no problems decorating with witches, ghosts, vampires, and the like. Nothing wrong with Halloween whimsy and fun!