Final answer:
Paul was asking Philemon to give up his legal rights over the slave Onesimus, which was a challenging request due to the social and legal implications of such an action in Roman society.
Step-by-step explanation:
The politically challenging thing that Paul was asking Philemon to do was A) give up his legal rights over Onesimus. The letter to Philemon is an appeal from Paul for mercy and manumission of Onesimus, a slave who had run away from Philemon, become a Christian, and started assisting Paul. Paul’s request would have put Philemon in a difficult position both socially and legally, as releasing a slave was not a common practice and could impact Philemon’s status and assets. The radical message of early Christianity, as seen in the Acts of Thecla and Paul, often conflicted with traditional Roman values, challenging social hierarchies and norms such as slavery.