Here is an interesting quote from Marcus Borg's book Reading the Bible Again for the First Time:
Paul's execution in Rome merits pondering. Was Rome simply mistaken in killing him? Was the execution based on a misunderstanding? Was it due to the decree of a crazed and callous emperor? Was Paul and his message actually harmless to the empire that killed him? Was it all about words--about calling Jesus "Lord" and refusing to give Caesar the same honor? Or was it about something much deeper and more important?
Certainly Paul and his small communities scattered through Greece and Asia Minor posed no immediate political threat to Rome. But did Paul's proclamation of a rival Lord and a rival social vision genuinely and ultimately threaten the imperial vision of life?
We who live after centuries of Christian accommodation with imperial systems are inclined to think that Rome simply made a mistake--that Rome failed to recognize that Christianity is harmless to empire (and maybe even helpful). But what happened to Jesus and Paul should give us pause. Christianity is the only major religion whose two most formative figures were executed by established authority. Accident? Plan of God? Or is there in Jesus and Paul a vision and a program, a message and a mission, that should cause systems of domination, ancient and modern, to tremble? (emphasis added)
Borg's allusion to "centuries of Christian accommodation with imperial systems" is itself quite interesting and also quite true. How Christianity evolved from a small movement of Empire resisters to become the official state religion of that same Empire is itself an interesting question to ponder. (In the modern era, the continued association with certain elements of Christianity with imperial systems continues. The ruler of the most powerful Empire of the present time claims to be a Christian and thus a follower of the religion of Jesus and Paul. Of course, not all of Christianity is guilty of collusion with Empire, and a social justice component has always been an important part of Christianity as well.)
Borg also implies that the mere words of Jesus and Paul seem hardly to have served as much of a threat to imperial Roman power. John Dominic Crossan, in his book Who Killed Jesus?, makes a similar point: the Romans did not concern themselves too much with those who merely said things. On the other hand, they were brutally repressive against those who acted in ways that challenged imperial authority. He cites the example of a different man named Jesus, who, in the year 62 wandered around Jerusalem proclaiming a dire fate for the Temple and lamenting "Woe to Jerusalem". He was brought up on charges for possibly seditious behavior, which could have gotten him executed. As Crossan puts it, "But this is only speech, not action...Roman authority finds it all politically irrelevant, judges the man mad, and lets him go free." The Romans were not so magnanimous with Jesus or with Paul. (Nor were they so magnanimous with John the Baptist.)
The conclusion is clear: Jesus and Paul challenged the prevailing authority of the Empire of their time. I would argue that to follow in the footsteps in Jesus means to challenge the Empire of the present time.