What makes you say the Bible is pro-slavery?
The Bible.
"Slaves, be obedient to those who are your earthly masters, with fear and trembling, in singleness of heart, as to Christ." (Ephesians 6:5)
"Let all who are under the yoke of slavery regard their masters as worthy of all honor, so that the name of God and the teaching may not be defamed." (Timothy I 6:1)
"But every slave that is bought for money may eat of it after you have circumcised him." (Exodus 12:44)
"When you buy a Hebrew slave, he shall serve six years and in the seventh he shall go out free, for nothing." (Exodus 21:2)
"When a man sells his daughter as a slave, she shall not go out as the male slaves do." (Exodus 21:7)
"When a man strikes his slave, male or female, with a rod and the slave dies under his hand, he shall be punished. But if the slave survives a day or two, he is not to be punished; for the slave is his money." (Exodus 21:20-21)
"If a man lies carnally with a woman who is a slave, betrothed to another man and not yet ransomed or given her freedom, an inquiry shall be held. They shall not be put to death, because she was not free." (Leviticus 19:20)
"As for your male and female slaves whom you may have: you may buy male and female slaves from among the nations that are round about you." (Leviticus 25:44)