Final answer:
Emperor Diocletian outlawed Christian religious services and put many Christians to death, initiating the Great Persecution in 303 AD in an attempt to reinforce Roman religious traditions.
Step-by-step explanation:
The emperor who outlawed Christian religious services and put many Christians to death was Emperor Diocletian. He initiated what is known as the Great Persecution, beginning in 303 AD, ordering the destruction of Christian buildings, the burning of their sacred texts, and subjecting Christians to torture, death in gladiatorial contests, and other brutal forms of executions. Diocletian aimed to reinstate religious orthodoxy and believed that Christianity threatened the stability of the Roman Empire. His efforts to wipe out the Christian faith, however, were ultimately unsuccessful, and the persecution officially ended with the issuance of an edict in April 311 by Emperor Galerius, who granted Christians the right to practice their religion.