After the Great Fire in Rome there were rumours in the city. People were thinking that it was the emperor Nero himself, who started the fire (in order to be able to build a new castle for himself.)
Because Nero wasn't able to find a real reason for the Great Fire, he blamed the Christians and they were persecuted soon after. This was possible because the Christians were a new culture and didn't believe in the Roman gods. This made them impopular and an easy scapegoat.