3 Then Paul said to him, “God is going to strike you, you whitewashed wall! Are you sitting to judge me according to the law, and yet contrary to the law you order me to be struck?” 4 Those who stood by said, “Would you revile God's high priest?” 5 And Paul said, “I did not know, brothers, that he was the high priest, for it is written, ‘You shall not speak evil of a ruler of your people’” (Acts 23:3-4).
Traditionally, Americans feel free to ridicule gov't officials. Indeed, you even have professional political satirists and cartoonists.
However, some Christians think, based on passages like Acts 23:3-4), that Christians citizens should always speak respectfully about gov't officials.
The passage is tricky to interpret. It seems implausible that Paul didn't recognize the high priest. If that's the case, it's natural to construe his disclaimer as sarcastic. A backhanded compliment.
One objection to that interpretation is that it means Paul willfully disregarded Exod 22:28. However, that injunction may envision an ideal situation. A just ruler. There's a prima facie prohibition against cursing your rulers. But like some other Biblical commands and prohibitions, that's implicitly conditional, because it takes for granted a particular situation. If the ruler is a travesty, then all bets are off. Certainly the OT prophets and Historical Books have harsh things to say about corrupt rulers. And Paul was a prophet in his own right.
To some degree, how commentators construe Paul's behavior mirrors the outlook of the commentator. More straight-laced commentators think Paul was sincere; more cynical commentators think Paul was sardonic.
At the very least, I think this exchange is too ambiguous to settle the question of how Christians ought to address their rulers. And I myself think Paul's retraction was sarcastic. Feigning innocence. I think Paul was consistently mocking the high priest, as a perversion of his office.