"I will set no evil thing before me" if you think everything about Halloween is evil then it is, to you. Kids dressing up for fun and going trick-or-treating I don't see as evil. Parents are coming up with some very proper cool ideas for costumes lately, all done for fun.You put "perfect" and "true" in quotations. Words I did not use.
You want concepts?
Christ is the Master and Model of Christian behavior. End of story.
Therefore, it would seem to me that the Word made flesh may have an opinion or two about Freddy Krueger.
"I will set no evil thing before me" was the first that immediately came to mind, but I could probably do this all day.
Everything about Halloween is pagan and antichrist.
You are free to disagree.
Someone can take anything and introduce evil in it, like even cartoons, and it's up to the parents to draw the line. It would be good if more churches offered a HarvestFest, but I'm sure most churches are on budgets or don't have the capacity.