As Christianity gained a foothold in the consciousness of the ancient world, the Roman authorities initially reacted slowly. As Jewish Christian migrations, and certainly the work of Peter, brought the new cult to Rome, it became largely identified with the Jews. As the Jews, with their one god concept, and refusal to adopt the Roman Caesar worship ideology, were so largely associated with the early Christians, the new cult got off to a very inauspicious start. This refusal of typical Roman religious custom wasn't just an issue of a damaged ego for the Roman elite, but a serious undermining of the religious tradition incorporating the ideas of many cultures and practices. The Romans had little concern over either Jewish or Christian practices on their own; it was their steadfast dedication to their own gods that would eventually lead to problems.
The relationship of early Christianity to the Jewish faith, and the foundation of the cult deeply rooted in a people accustomed to religious intolerance actually helped it take hold initially. The Jews were accustomed to resisting political authority in order to practice their religion, and the transition to Christianity among these people helped foster the sense of Imperial resistance. To the Romans, Christians were a strange and subversive group, meeting in catacombs, sewers and dark alleys, done only for their own safety, but perpetuating the idea that the religion was odd, shameful and secretive. Rumors of sexual depravity, child sacrifice and other disturbing behavior, left a stigma on the early Christians. Perhaps worst of all was the idea of cannibalism. The concept of breaking bread originating with the last supper, partaking of the blood and body of Christ, which later came to be known as Communion, was taken literally. To the Romans, where religious custom dictated following ancient practices in a literal sense, the idea of performing such a ritual as a representation was misunderstood, and the early cult had to deal with many such misperceptions.
The first mention of Christians from a perspective of Roman government intervention occurred under Claudius. The limited description is provided by Suetonius, the somewhat gossip oriented historian of the 'Twelve Caesar's":
"Since the Jews were constantly causing disturbances at the instigation of Christ, he (Claudius) expelled them from the city (Rome)."
Despite this, Christians remained in Rome, and by the reign of the next emperor, Nero, the first major incident of Christian persecution took place in 64 AD. The fire that ravaged Rome in that year, and the subsequent building of Nero's golden palace on the destroyed property, was wildly unpopular in Rome. Many placed blame directly on Nero, accusing him of intentionally lighting the fire, in order to build his palace. Nero, seeking an unpopular scapegoat, turned the blame on the subversive Christians, playing on people's fears that their intention was the complete destruction of the Roman world as they waited for the judgment day. Tacitus the invaluable Roman historian, writing years later, described Nero's response with some detail:
"Neither human resources, nor imperial generosity, nor appeasement of the gods, eliminated the sinister suspicion that the fire had been deliberately started. To stop the rumor, Nero, made scapegoats--and punished with every refinement the notoriously depraved Christians (as they were popularly called). Their originator, Christ, had been executed in Tiberius' reign by the Procurator of Judaea, Pontius Pilatus (who was actually a Praefectus, not a Procurator). But in spite of this temporary setback, the deadly superstition had broken out again, not just in Judaea (where the mischief had started) but even in Rome. All degraded and shameful practices collect and flourish in the capital. First, Nero had the self-admitted Christians arrested. Then, on their information, large numbers of others were condemned--not so much for starting fires as because of their hatred for the human race. Their deaths were made amusing. Dressed in wild animals' skins, they were torn to pieces by dogs, or crucified, or made into torches to be seton fire after dark as illumination.... Despite their guilt as Christians, and the ruthless punishment it deserved, the victims were pitied. For it was felt that they were being sacrificed to one man's brutality rather than to the national interest."
Suetonius added his own short confirmation:
"punishments were also inflicted on the Christians, a sect professing a new and mischievous religious belief."
This persecution wasn't aimed directly at the Christians in order to drive them out of Roman consciousness. Instead they provided an easy alternative target to the blame, which was being cast directly on the Emperor. Still, Tacitus' description provides an in-depth look at the early Roman perception of Christianity. As he suggests, however, Nero's violence likely did little to stop the spread, but instead helped spur its growth.
Under Domitian, just a generation later, some sources indicate another persecution directed at Christians. Operating with the knowledge that Christians refused adhering to the Imperial Cult of Caesar worship, Domitian may have launched an investigation, sending a team to Galilee to discover the roots of Jesus. Though evidence is sketchy, it does indicate at least a general knowledge and adversarial relationship between the Emperor and the cult. Domitian has also been accused of mass executions of Christians, which is true, but it wasn't necessarily a purge targeted at that single group. Domitian ruled in an almost tyrannical reign of terror in which many perished, not just Christians. Political enemies, 'divisive' groups and individuals of all kinds met terrible fates. Though he too, may have used the excuse of Christianity to justify some murders, there is little evidence that he had a personal agenda against the cult.
Shortly after Domitian, the Emperor Trajan and the Governor of Bithynia-Pontus, Pliny, leave a record of Imperial attitude towards Christianity. In this period, Trajan forbid meetings of secret societies, and their potential for subversion, which would include the Christians. Though Trajan's reign indicates a slight shift towards tolerance, there is little doubt that Christianity created problems for the administration and led to punishment for those who practiced it. Pliny writes in a letter to Trajan (c. 112 AD):
"I have never been present at an examination of Christians. So, I do not know the nature or the extent of the punishments usually dealt out to them, nor the grounds for starting an investigation and how far it should be carried...For the moment this is the line I have taken with all persons brought before me on the charge of being Christians. I have asked them in person if they are Christians; if they admit it, I repeat the question a second and a third time, with a warning of the punishment awaiting them. If they persist, I order them to be led away for punishment; for whatever the nature of their admission, I am convinced that their stubbornness and unshakeable obstinacy ought to be punished. There have been others similarly fanatical who are Roman citizens; I have entered them on the list of persons to be sent to Rome for punishment.... I considered that I should dismiss any who denied that they were or ever had been Christians, once they had repeated after me a formula of invocation to the gods and had made offerings of wine and incense to your statue (which I had ordered to be brought into court for this purpose along with images of the gods), and furthermore had cursed the name of Christ. Real Christians (I understand) can never be induced to do these things....They declared that the sum total of their guilt or error amounted to no more than this: they had met regularly before dawn on a fixed day to chant verses alternately among themselves in honor of Christ as if to a god, and also to bind themselves by oath, not for any criminal purpose, but to abstain from theft, robbery and adultery, to commit no breach of trust and not to refuse to return a deposit upon demand. After this ceremony it had been their custom to disperse and later to take food of an ordinary harmless kind. But they had in fact given this up since my edict, issued on your instructions which banned all political societies. This made me decide it was all the more necessary to extract the truth from two slave women (whom they call `deaconesses' by torture. I found nothing but a degenerate sort of cult carried to extravagant lengths... I have therefore postponed any further examination and hastened to consult you..."
Trajan replies giving evidence of a general procedure of punishment for Christians, while also indicating that there is no need to seek them out:
"You have followed the right course of procedure, my dear Pliny, in your examination of the cases of persons charged with being Christians. For it is impossible to lay down a general rule to a fixed formula. These people must not be hunted out. But if they are brought before you and the charge against them is proved true, they must be punished. But in the case of anyone who denies that he is a Christian, and makes it clear that he is not, by offering prayers to our gods, he is to be pardoned as a result of his repentance--however suspect his conduct may have been in the past. But pamphlets circulated anonymously must play no part in any accusation. They create the worst precedent, and are quite out of keeping with the spirit of our age."
Trajan's successor, Hadrian, seems to have continued a mostly indifferent approach to Christianity, provided they didn't engage in open hostility. Instead, massive uprisings of Jews led to harsh punishment. This punishment meted out to the Jews, involving massive expulsions from eastern settlements, is clearly identified as separate from Christianity. This is important in that, the Christians by now were growing beyond the Jewish roots and was becoming more and more a religious option for Gentiles. Still though, Hadrian and those in authority still must've identified some Jews and Christians as part of the same group and its impossible to think that some Christians didn't meet a similar terrible fate under his rule.
Under Marcus Aurelius, the so-called stoic emperor, Christianity continued to be identified in a similar way to that of Trajan and Hadrian. Marcus Aurelius, however, had a personal dislike of Christianity, and though he continued the practice of not seeking them out for punishment, persecutions during his reign, especially those in Lyons (c. 177 AD) were particularly bloody. Shortly thereafter, in the reign of Commodus, who was much maligned for personal debauchery, there seems to be a slight shift in favor of Christians. By this time, the religion was definitely beginning to become more common among Romans of means and influence. A concubine of the Emperor, by name of Marcia, apparently negotiated the release of Christian mine workers, who must've lived under deplorable conditions.
Though the attitude towards Christianity was beginning to change, wide spread acceptance was still a long time off. Some sects, such as the Montanists of the 2nd century adhered to encouraging death by persecution. Not only would this advance the faith through martyrdom, it would bring the victim closer to Christ, by following in his footsteps. By the later 3rd century, however, Christian persecution from imperial sources was beginning to decline. Instead the infighting between various sects of the faith became the source of persecution. The Pagans too, in much later periods, would suffer as terrible atrocities as the early Christians. Despite this switch, one more great persecution was still to occur. Under the Eastern Emperor Diocletion, beginning in 303 AD and lasting for 8 years, he and his successor Galerius began a systematic purge of Christians. While many certainly perished, most were displaced from home and property. Many migrated west where the Imperial authority was more tolerant by this point. However, in places like Syria, Egypt and Asia Minor, the Christians certainly suffered terribly. Diocletion though, seems to have relented as he approached his own deathbed. He ordered the discontinuation of his aggressive policy, if only the Christians would pray to their god on his behalf. This final persecution against the now massive religion would soon be supplanted by the coming of Constantine and would not yet gain Imperial favor but certainly complete tolerance.
Despite the sporadic persecutions, Christianity was persistent. Between the beginning of the cult through the Great Persecution of Diocletion, some estimates have placed the death toll as high as 100,000 people during that period. Others, like the ancient source Origen, list the number of Christian martyrs simply as 'relatively few'. Edward Gibbon, the 18th century writer lists the number at 'less than 2000', but the truth of the matter will never be known for sure and these numbers are also dependent on semantics. Some viewed the concept of 'martyrdom' as any Christian who had been killed for any reason. Others defined it more conservatively as only those that were executed in defense of their religion. Regardless, by 337 AD and the ascension of Constantine as sole Emperor, the population of the Christian world continued to surge forward. As many as 25 to 30% of the population of the Roman Empire (15 to 20 of 60 million people) has been estimated as being Christian. Together with other similar monotheistic cults, like those of Mithras and Sol Invictus, the old Pagan traditions were slowly becoming a thing of the past. The church too, would do everything in its power to be sure of its continued path to dominance, and the tables would be completely turned on both traditional Pagans and dissenting 'heretics'.