Answer: Because Christianity only worships only one god while Roman worshiped more than one god
Step-by-step explanation:
The rapid spread of Christianity to five factors: (1) the promise of salvation and eternal life for everyone was an attractive alternative to Roman religions; (2) stories of miracles and healings purportedly showed that the one Christian God was more powerful than the many Roman gods; (3) Christianity began as a grassroots movement providing hope of a better future in the next life for the lower classes; (4) Christianity took worshipers away from other religions since converts were expected to give up the worship of other gods, unusual in antiquity where worship of many gods was common; (5) in the Roman world, converting one person often meant converting the whole household—if the head of the household was converted, he decided the religion of his wife, children and slaves.