Explanation:

The emperor Decius decided that Rome had lost it's way and the only way to save it was for everyone to make a sacrifice to the gods.

Once you had made your sacrifice you got a paper slip from the government.

Christians refused in huge numbers. They were slaughtered, including the pope at the time.

edit: I just want to add, it's OC so excuse the crappy image editing. :D

Decius: "Oh boy, I'm sure sacrificing to the gods in these perilous times will bring us all together and grant my reign the unity it needs to keep the Empire together!"