Gibbon: Why was Christianity successful?

Gibbon states that there were five reasons why Christianity thrived in the Roman Empire.

I.Christianity was inflexible. It derived its intolerant zealotry from its Jewish heritage and this was decidedly unlike the inclusive polytheism of the pagan religions which most Romans practiced.

II. The doctrine of a future life. The idea of a Christian heaven was a powerful and coercive tool for recruiting new believers.

III. The miraculous powers attributed to the early Church. Even after the death of Jesus there were frequent reports of resurrections and miracles happening in the Holy Land as Gibbon recounts. Eventually the Christian elders/leaders (presbyters) put a stop to these claims to avoid discrediting the church.

 IV. The pure and austere morals of the Christians. The rigidity of the Christian faith was appealing to many. In addition, pagan religions often had priests from the upper caste of society and the hoi polloi were allowed limited access to temples and ceremonies. In contrast, Christianity embraced the poor and encouraged the divestment of material (temporal) positions. Living an austere life was a way to gain access to the eternal kingdom.

V. The union and discipline of the Christian republic. The first few hundred years of Christianity were very tumultuous, with many beliefs competing for control of the young religion. Eventually a clear set of doctrines emerged which promoted the cohesion of the church.  Having one set of church doctrines and leaders made Christianity less ambiguous, more transparent and contrasted it from pagan religions of the day.

That being said, the early church was not initially very unified. Perhaps the most prolific splinter group were the Gnostics who combined Christianity with eastern philosophy. According to Gibbons there were over 50 sects at one point with names such as the Basilidians, Valentinians, Marcionites and later the Manicheans. Each of these had their own gospels, bishops, martyrs and had influence and proselytes from Asia to Rome (and beyond). Eventually the Catholic sect (for lack of a better word) emerged dominant and unified most of Christianity under a single set of tenets. The reason for this is largely due to the list stated above, which the other sects were not able to incorporate as successfully.

The Catholic Church had two powerful weapons at its disposal to keep the faithful in line and maintain their unity: Excommunication and Absolution of sins. Anyone excommunicated would be ostracized from the Christian community, excluded from all rights, privileges and fellowship. More significantly, the pariah would feel the onerous burden of eternal damnation unless he was received back into "communion" with the church. Forgiveness of sins was the second tool of the church which granted it the ability to completely pardon anyone for any worldly (temporal) crime. To be able to absolve someone of any crime (theft, murder, etc) with the authority of god was incredibly powerful in recruiting new members and a sacrament that could be withheld on those members who did not conform.

For these reasons, Christianity flourished in the Roman Empire over other religions, despite the persecution they endured. 

Gibbon does make a point of acknowledging that the familiar story of the birth of Jesus was a well-known tale in the mythology of several other religions even before Christ was born.

"...the legends of Bacchus, of Hercules, and Aesculapius had, in some measure, prepared their imagination for the appearance of the Son of God under a human form". 

Below is a video which follows this up in more detail. 

http://www.youtube.com/watch?v=D1FdtpH8lSI&feature=related