You seem to be taking a rather light approach to the devil. Scripture doesn't recommend that.
For example:
1Pe 5:8 Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour:
1Pe 5:9 Whom resist steadfast in the faith, knowing that the same afflictions are accomplished in your brethren that are in the world.
Eph 6:11 Put on the whole armor of God, that ye may be able to stand against the wiles of the devil.
Eph 6:12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
That, my friend, is part of the problem of Halloween. We've "mocked" the devil into cuteness. We've likened him to a cartoon character. We've reduced his reality to a characticture. Do you think he cares that we've succeeded in picturing him as not a dangerous adversary? He loves it. It makes his job much easier.
Christians have an amount of protection, but we are still to be wary, vigilent. Of course, it's open season on non-Christians. Halloween IS a high holy day for Satanists. Tell me:
2Co 6:14 Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
2Co 6:15 And what concord hath Christ with Belial? or what part hath he that believeth with an infidel?
2Co 6:16 And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.
2Co 6:17 Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you.
Why do you have agreement with Satanists?
I haven't seen one to agree with.