This has been a long standing topic for me... I used to believe it was 'evil' along with Christmas trees etc. And then, I started to see and believe that this was short sighted and that Christ has a way of redeeming what the devil meant for evil. Yes, the origins of both are pagan, but the origin is not what we celebrate today. The bible does say to avoid the very appearance of evil, and certain costumes and 'tricks' should be avoided, but as a whole, we celebrate kids dressing up to have fun and to get free candy. And pumpkins. None of these children, and nearly no adults, even realize or contemplate the origins. And as such, Christ redeemed an evil thing. Same for the Christmas tree.