Why did the Roman Empire suddenly believe in Jesus after previously killing him?

 The belief in Jesus within the Roman Empire did not happen suddenly. The process of Christianity spreading and gaining followers in the Roman Empire was gradual and occurred over several centuries. The events surrounding Jesus' crucifixion and the subsequent growth of Christianity can be outlined as follows:

1. **Life and Crucifixion of Jesus:** Jesus, according to Christian belief, lived in the first century AD and was crucified by the Roman authorities. His teachings and the accounts of his resurrection started to gain followers.

2. **Early Christian Communities:** After Jesus' death, his followers formed small communities and began spreading his teachings. The earliest Christians were predominantly Jewish, and their movement was initially centered in the eastern part of the Roman Empire.

3. **Spread of Christianity:** The Apostle Paul played a crucial role in spreading Christianity beyond Jewish communities. His missionary journeys took him throughout the eastern Mediterranean, and he preached to both Jews and non-Jews (Gentiles). Paul's efforts contributed significantly to the expansion of Christian communities.

4. **Conversion of Constantine:** One of the most pivotal moments in the history of Christianity within the Roman Empire was the conversion of the Roman Emperor Constantine in the early 4th century. In 313 AD, the Edict of Milan, issued by Constantine and his co-emperor Licinius, granted tolerance to all religions, effectively legalizing Christianity.

5. **Council of Nicaea (325 AD):** Constantine played a role in convening the First Council of Nicaea in 325 AD, where Christian leaders gathered to address theological disputes and establish a unified understanding of Christian doctrine. The Nicene Creed was formulated during this council.

6. **Official Religion of the Empire:** In 380 AD, Emperor Theodosius I declared Christianity, specifically Nicene Christianity, to be the official state religion of the Roman Empire through the Edict of Thessalonica.

The transition from Jesus' crucifixion to Christianity becoming the official religion of the Roman Empire was a gradual process influenced by a combination of social, political, and cultural factors. It involved the efforts of early Christian communities, key figures like Paul, and the support of influential leaders, culminating in the acceptance and endorsement of Christianity by Roman emperors.