@SW-User It shouldn't be argued that slavery was only taking place in the time of the Law of Moses because there were guidelines to having slaves in the Christian scriptures as well. In fact it was much more common then.
Slavery was much more common in the Roman Empire than in the time of the ancient Hebrew scriptures. Individuals could own hundreds or thousands of slaves. The imperial government's position on the institution of slavery in the time of the first century Christians was not challenged by Christians. They respected the legal rights of others, including other Christians, to own slaves.
The apostle Paul sent back the runaway slave Onesimus, who had become a Christian and willfully returned to his master, also a Christian. (Philemon 10-17) Paul admonished Christian slaves not to take improper advantage of their Christian masters (1 Timothy 6:2) Christian masters were obligated to deal fairly with their slaves. (Ephesians 6:9; Colossians 4:1)
All Christians, regardless of their social status, slave and free man, were the same and of equal standing. (1Corinthians 12:12, 13; Galatians 3:28; Colossians 3:11)