Fire Jesus is essentially real Jesus with two major differences; the ability to shoot flames, and the psychotic tendency to burn Pagans. He will spend vast amounts of time simply hunting down and burning Pagans with flames that spurt from his palms.
Pagan: Man, I sure am ready for a long day of bettering my society as a whole followed by some naturalistic tree worship!
Fire Jesus: My ass you are! *shoots flames which instantly incinerate said Pagan"