First of all, the devil has no day. Every day belongs to Jesus.
Second, Christians are told to crucify their flesh, to live spiritual, not carnal lives. The sinner gives free reign to his flesh. There’s no death going on as you’re getting drunk with plastic vampire teeth in your mouth. The blood is fake.
But what Christians are doing is real. These verses sounds pretty Halloweeny:
We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life.
For we know that our old self was crucified with him so that the body ruled by sin might be done away with, that we should no longer be slaves to sin—
In the same way, count yourselves dead to sin but alive to God in Christ Jesus. — Ro. 6:4, 6, 11 NIV.
Do you think your party celebrating death-things is cool once a year? You should celebrate a real death 52 times a year (every Sunday).