What about slavery in the Bible?
The Case of Onesimus in the New Testament
1 Corinthians 7:21 Art thou called being a servant? care not for it: but if thou mayest be made free, use it rather.
Paul exhorts slaves who are able to avail themselves of any opportunity to gain their freedom. It was not one to be desired but only endured out of necessity.
If you turn to Philemon 1:10-16, you will see that Paul softens the act of Onesimus running away from his master by calling it a departure. He suggests that it was possible that it was permitted in Divine Providence in order that he be brought under the influence of the gospel, and be more serviceable to Philemon as a Christian. In verse 14, I think that Paul does suggest to Philemon that he free Onesimus, but he clearly does not command it. Had he commanded it, this would have meant that there was clear apostolic precedent in precept and in practice that Christians must free their slaves.
The words of Paul in the epistles are given by inspiration of God, and the Spirit is certainly able to cause the writers to transcend their cultural norms and biases, but there is a reason for why Paul did not write epistles condemning slavery. It would had subverted the gospel and derailed its core into a radical social movement about manumission, rather about the good news of Christ Jesus. Consider how around 40% of the Roman empire were slaves. The Holy Spirit did not get Paul to make evangelism a social agenda of society.
However, what the gospel brings about changed lives, and Paul says in verse 8 that he is bold enough in Christ to command you to do what is required. What would that be? The verses that follow speak of Paul wanting Philemon to act from his goodness, not by necessity or compulsion 'but willingly' (verse 14).
He wants Philemon to receive Onesimus back 'Not now as a servant, but above a servant, a brother beloved' (verse 16). Still he does not command manumission, but suggests it by reminding Philemon that he (Philemon) owes himself to Paul, and that 'I wrote unto thee, knowing that thou wilt also do more than I say' (verse 21). What would Philemon think to do next? Paul suggests it, and you could say that he was close to commanding it.
But it is not commanded because such an apostolic command would truly have made the Christian faith at that point all about emancipation of slaves. And such is not the message of the gospel but it is, properly, an effect of the gospel.