Christianity has its roots in the Monotheistic (meaning that they recognize only one God as existent and supreme) Judaism. The Jewish religion had many observances and rituals, including the Ten Commandments, a basis for daily life, and the observance of the rest day of the Sabbath. There were a few sects, one known as the Pharisees, the Sadducess, and the Essenes. The Sadduccees were an aristocratic party, while the Pharisees were more of commoners. However, both were regarded higher in society than any of the other people.
Jesus of Nazareth (c.3BC-36AD) Reformed Judaism, and essentially founded Christianity. During his life he broke many of the rules of not working on the Sabbath, and taught to do things contrary to the practices of the Pharisees and Sadducees. He often publicly rebuked the religious rulers, which earned him many enemies. In addition to this he also affiliated himself with sinners, and women, which the hairesis looked down upon.
The Apostle Peter (c.BC-67AD) was a disciple of Jesus. He knew Jesus during his time on earth, and walked with him. Peter is considered by many to be the first overseer of the church after the death and ascension of Jesus. Peter was eventually crucified upside down.
The Apostle Paul (c.5-66AD) began as an adamant persecutor of the church. However, he was eventually converted as a result of seeing Jesus in a vision. After his conversion Paul began to preach Christ. He was imprisoned. During his imprisonment he wrote many of the books of the New Testament, which were written as letters to churches across the Asia, Rome, and Greece. Paul's life ended when he was put to death by Nero.
Peter and Paul, while being united in Christ, did not always get along well. While they did not disagree on who could be a Christian, they had different people who they attempted to reach. Peter was called to be an apostle the Jews, and Paul was called to evangelize to the gentiles. In one instance Peter began to associate himself with only Jews, which earned him a public rebuke from Paul.
Following Christ's death the church faced mass persecution from the Roman government. Many of the Christians went into hiding, including the disciples. They met in secret, and held their practices in secret. However, they eventually they became bold in the face of persecution. They loved their lord more than their lives, even until the point of death.
The Romans liked having Stoicism coinciding with Christianity because it gave them an alternative than to join Christianity while also giving them a sense of purpose to life. It also gave them a means of practicing rituals and prayers, while studying proverbs, in order to gain inner peace.
Neoplatonism was also popular in Rome. It gave Christians and Pagans alike the ability to practice their religion while also giving them a means of exercising mental, and intellectual growth.
In 313 AD Constantine issued the Edict of Milan, which made it legal to openly practice Christianity in the Roman Empire. This was a major turning point. No longer was the Christian religion in danger of being snuffed out, in fact, this was part of what enabled the religion to flourish, when by all natural accounts it ought to have been ended swiftly.