What were some reasons for the rise of christianity in the roman republic?

Hunger for truth. That is the reason for the rise of Christianity worldwide.

REAL REASON: Emperor Constantine was converted to Christianity Circa 300 AD.

When the most powerful man in the world is a Christian....

There ceased to be a Roman Republic (civil war, Pax Augustus aka Pax Romana), by the time Jesus was born in Bethlehem. The Apostles of Christ were instrumental in spreading the Christian faith.

1. Acts of martyrdom actually inspired the blood thirsty Roman citizens (those who enjoyed watching gladiatorial games). "How were some Christians able to die so gracefully?", were probably some things running through a Roman's head as he walked home from a show. "Who was this Christ?"

"The persecution of Christians under the Roman civil authorities lasted from around 64 to 312...Christians, from the earliest times, considered martyrdom, the baptism of blood, as an equivalent to baptism by water when one had not received it before martyrdom." [Spiteri, 5]

2. System of governance by a hierarchy of bishop-presbyters and deacons, developed early, based on Sacred Scripture. [cf. Spiteri, 6]

3. Rooting out heresies perhaps instrumental to the Church's development (as opposed to what may people consider as detrimental and socially regressive; you know how when the Church says, gay marriages is wrong, and women cannot be ordained as priests and people react out that the Church is socially backward and regressive). Heresies: docetism, gnosticism, manichaeism, donatism. [cf. Spiteri 11-13]

4. Roman politics: Romans just became decadent, and corrupt. Meanwhile Christians were living as hermits in the desert i.e. St. Anthony. The Edict of Milan meant that Christians can no longer be persecuted. Constantine the Great defeating Maxentius, and that Constantine the Great attributing his victory to the Christian God.

5. Rise of Christian because of Classical Church Doctors, "Doctors of the Church" such as St. Ambrose, St. Augustine, St. Jerome and Pope St. Gregory the Great.

Roman Empire, and even though Christianity gained a significant following as a seditionist movement, the empire had many enemies, it would never have grown into the monolith it did without the empire and later the kings championing it

The Romans were tired of their fake, do-nothing gods, so they adopted another fake, do-nothing god.

They made Christianity sound better by mixing some pagan mythology in with it. That's why the Jesus story in the bible sounds just like Mithra the son of god.

1) Hundreds of years before Jesus, according to the Mithraic religion, three Wise Men of Persia came to visit the baby savior-god Mithra, bring him gifts of gold, myrrh and frankincense.

2) Mithra was born on December 25 as told in the “Great Religions of the World”, page 330; “…it was the winter solstice celebrated by ancients as the birthday of Mithraism’s sun god”.

3) According to Mithraism, before Mithra died on a cross, he celebrated a “Last Supper with his twelve disciples, who represented the twelve signs of the zodiac.

4) After the death of Mithra, his body was laid to rest in a rock tomb.

5) Mithra had a celibate priesthood.

6) Mithra ascended into heaven during the spring (Passover) equinox (the time when the sun crosses the equator making night and day of equal length).

Anytime you have a leader of a religion who comes back to life after you've crucified him, the religion is going to get a massive following. I guess you could call it The Wow Factor--on steroids.

It wasn't a republic, for one thing. It hadn't been one since Julius Caesar. Christianity rose because the emperor at the time, Constantine, needed a uniting force within the empire to keep it together. The relative new religion of Christianity, with its emphasis on equality of all people, was just the thing he was looking for. So Constantine not only made this upstart religion legal, he proclaimed it the official religion of the Empire, which means that Everyone within the empire had to become Christian or face severe punishment if not death.

Constantine saw a vision of the cross. and there were church "fathers" so-called that manipulated the emporer to make christianity a state governed religion. but in doing so, they had to manipulate him into destroying the libraries of the nations! (to get rid of the Competitition.) and they had to allegedly change some of the biblical and gospel doctrines, like eating flesh of animals and drinking alchohol.

Constantine, the Roman Emperor, gave it validity...

Without it, it' anyone's guess where it would be today...

IMHO

Well, if you open this Magazine, you'll might get a good understanding under


A first-century Christian preaching at a seaport
Preparing the Nations for “the Teaching of Jehovah”

http://www.jw.org/en/publications/magazines/w20150215/preparing-nations-teaching-of-jehovah/

Unlike Judaism, no circumcision required; unlike Mithraism, it accepted women. It promised blissful afterlife for followers - always an attractive package. Once Emperor Constantine converted, the ballfield was tilted inexorably toward Christianity.

It had the right formula for success. There were a lot of slaves in Rome. Christianity appeals to slaves with its promise of a better afterlife. Christianity is also useful for the ruling class because it keeps the slaves from trying to better their lot in this life.

Because Christians were so happy to die for Christ. They even fought each other for the honor.