Some Christians seem to think that slavery meant that the slaves were merely "servants" and similar to modern day employees. The logical conclusion is that people must have been lining up to be come a slave "Oh, chose me! I want to be your slave! I have all the qualifications that you want."
Historian Robin Lane Fox in "Pagans and Christians in the Mediterranean World" (Penguin:2006) disagrees. This is what he states about slavery during the time period of Jesus and the early Christian church: ....
Paul's short letter to Philemon nowhere suggested that there was a Christian duty to free a slave, even a Christian slave. p. 295
Christian leaders did nothing to disturb [slavery]. When Christian slaves in an Asian church community began to propose their freedom should be bought from community funds, Ignatius of Antioch advised firmly against the suggestion. ... Christian leaders began from a principle of the equality of man, yet argued that worldly differences should continue undisturbed. The greater slavery was to man's passions. p. 296
... the accepted attitudes of some Christian leaders is not in doubt. It's priorities are not those of a faith concerned to free slaves from their masters, or to urge masters to let them be released. p. 297
Christian masters were not specially encouraged to set a slave free. ... Many masters required slaves to buy their freedom or to leave a child in their place, so that a younger slave could be bought or acuired on release of an older, wasting asset. p. 298
Not until the fourth century [CE] and the rise of monastic communities do we find clear hints of Chrisian attempts to better a slave's position. p.299
Among Romans, the most acceptable homosexuality was an act conducted by citizens on slaves and foreigners. [Not punishable by law] ... Before marriage a young man could also turn to prostitutes or slaves. p. 342
As men of all ages slept with their slaves, natural children were a widespread fact of life. p. 343
Further more the treatment of slaves in Jesus' time was dreadful, immoral and unethical yet neither Jesus nor Paul ever stated any thing against it.
The master's power over the slave was called (dominica potestas), and it was absolute. Torture, degradation, unwarranted punishment, and even killing a slave when he was old or sick, in the eyes of the law, slaves were property who could not legally hold property, make contracts, or marry, and could testify in court only under torture. The death of his master did not free a slave.
... Up to the days of Augustus, a marriage between a slave needed not be recognized by its master and enjoyed no protection in law. The children of such a couple would be born as slaves. A slave who ran away would face branding or possibly even death. The treatment of slaves was totally in the hands of the owner, and usually varied according to their abilities.
Roman law regarded slaves as mere chattels. They were subject to the will of their masters, against which they enjoyed no protection. Punishments inflicted upon slaves were merciless. Hard labour, whippings, branding, breaking of the joints or bones, branding of the forehead with letters denoting the slave as a runaway, liar or thief (FUG, KAL, FUR) and crucifixion were all punishments which were inflicted upon slaves. So too, being thrown to the wild beasts in the circuses or even being burnt alive in a cloak soaked in pitch.
the Roman view of slaves was one of contempt. Slaves were people one looked down upon. Kindness toward them was rare, even seen as a sign of weakness. ...
... There were several ways you could become a slave in Rome. Some became slaves because they could not pay back the money they had borrowed. The government would also take people into slavery if they could not pay their taxes. There were also many cases of poor people selling their children as slaves to richer neighbours.
... Roman generals in their campaigns abroad sent back thousands of captured soldiers to be sold as slaves.
Slave traders would follow the Roman army abroad on their campaigns. After a battle they would buy the defeated soldiers and their families, and then arrange for them to be sent back to Rome and the other major settlements in the empire.
It was common practice to have them in work-teams of ten slaves. Branded on the forehead, chained together and guarded by a foreman carrying a whip, there was little chance of escape.
Slaves who did manage to run away were guilty of theft (they had stolen their master's property), and if caught they would suffer terrible tortures as a means of frightening other slaves.
After Emperor Constantine became converted to Christianity, the life of slaves improved slightly. For example, a law was passed in AD 319 that made it illegal to kill slaves. Owners of slaves were also forced to stop branding their slaves on the face and instead had to put their mark on the hands and legs.
However, Christianity did not bring an end to slavery. Christians argued that Jesus never criticised slavery in his sermons. The Church not only refrained from attacking the system of slavery but continued to use large numbers of slaves to work monastery lands.
The bible does not tell the full story about slavery. They were not merely "servants" having a nice safe work evironment.