When Christian slaves in the early Asian Church suggested that community funds might be used to purchase their freedom, they were soon disabused of their hopes, a line supported by one of the greatest Church Fathers (Ignatius of Antioch.).He declared that their ambition should be to become better slaves, and they should not expect the Church to gain their liberty for them.We know of other slave owning Christians in various ways, for example one, Ausonius ,recorded having tattooed his recaptured runaway slave on the forehead (the significance seems to have been guilt about tattooing, because tattooing was banned by the bible) Pagan slaves who wanted to become Christians required permission from their masters.
His orthodox approach followed the words of St Paul: "Each one should remain in the situation which he was in when God called him. Don't let it trouble you although if you can gain your freedom, do so." (1 Corinthians -21 NIV).
When the Roman Empire became Christian under the Emperor Constantine, the institution of slavery remained unaltered, except for superficial changes.
Some 40 collars (or slave pendants) survive from antiquity, almost all of them from the fourth century, from Rome, Africa and Sardinia.
Many of the collars feature Christian symbols such the chi-rho christogram or a Christian cross, showing that the slave owners were Christians.
Soon the Church would become the largest slave owner in the Roman Empire.
Bishops themselves owned slaves and accepted the usual conventions. Slave collars dating from around AD 500 have been found in Sardinia, stamped with the sign of the cross. "I am a slave of Felix the archdeacon: hold me lest I run away".
Augustine called on the free to give thanks because Christ and his Church did not make slaves free, but rather made bad slaves into good slaves. Augustine teaching that the institution of slavery derives from God and is beneficial to both slaves and masters would be cited by many later Popes as evidence, indeed proof, of the acceptability of slavery.
It was an integral part of the Christian "Tradition" one of the main sources of authority in the Church.
In 362 AD a Church Council at Gangra in Asia Minor excommunicated anyone encouraging a slave to despise his master or to withdraw from his service.
This would in time be incorporated into Church Law, where it would remain from the 13th to the 20th century.
Exodus -21 If a slave is gored by a bull, it is the master, not the slave, who is to be compensated (Exodus ).