Perhaps they lack the subtlety of other groups, but the Candles of God have no desire to be subtle. Perhaps they do not keep their secrets very well, but the Candles of God want their voices to be heard. Perhaps they are careless about who they kill, but there shall be no innocent bystanders when the fires of hell consume the unrighteous.
The PCs are sent with a diplomat to another country to protect him and do his bidding. There may be some espionage, rescuing, downright bullying, etc. Could make a nice medieval, special operations background.