What's so evil about trick or treating? All the years I did it as a kid, not once did I think of any evil that went along with that day ... only about all the goodies that I got. :o)
I think God wants Christians to be a little discerning in what they celebrate.
Jer V2-3 Thus says the LORD: Do not learn the way of the Gentiles; Do not be dismayed at the signs of heaven, for the Gentiles are dismayed at them, for the customs of the people are futile [vanity, vain, worthless];
Gentiles at this time were those who did not know or have God. "Do not learn their ways". The ways of pagans are celebrating days like Halloween. I think the injunction still applies.
A similar prohibition is here:
When the LORD your God cuts off from before you the nations which you go to dispossess, and you displace them and dwell in their land, take heed to yourself that you are not ensnared to follow them, after they are destroyed from before you, and that you do not inquire after their gods, saying, How did these nations serve their gods? I also will do likewise. You shall not worship the LORD your God in that way; for every abomination to the LORD which He hates they have done to their gods; for they burn even their sons and daughters in the fire to their gods. Whatever I command you, be careful to observe it; you shall not add to it nor take away from it. (Deuteronomy 12.29-32)
Ahhh, you do admit to the "ritualization" of it. A form of worship, but to whom?
Thinking about the goodies all day when you were a kid? Greed? Gluttoney? What would you teach a child?
Childhood diabetes, poor dental health, childhood obesity, etc... The body is the temple of whom?