Original: In Rome, the office of Pontifex Maximus came to be reserved for the emperor, who was often declared a 'god' posthumously, or sometimes during his reign. Failure to worship the emperor as a god was at times punishable by death, as the Roman government sought to link emperor worship with loyalty to the Empire.
Simplified: When in Rome, the office of Pontifex Maximus was reserved for the emperor, failure to worship him as a god was sometimes punished by death, as the Roman government sought to link emperor worship with loyalty to the Empire.