From the Frontline-Episode 239-Halloween vs Reformation

From the Frontline: Halloween Vs Reformation

What is the origin of Halloween? What happens on Halloween? Should Christians be participating in Halloween celebrations? What else is 31 October famous for? Why is it so important to celebrate the Reformation? What would be appropriate ways in which we could mark Reformation Day?  

"Test all things; hold fast to what is good. Abstain from every form of evil."

1 Thessalonians 5:21-22