Although I don’t have any hard evidence, I do believe that I have no undue reason by which I cannot propose the following hypothesis in regard to Paul and his potential Yom Kippur sermon as recorded in the book of the Acts of the Apostles, based on a fairly reasonable timeline. I may have my chronology way off base (please let me know if I do), but here is what I am able to reconstruct, and by way of reconstruction assume a Yom Kippur sermon from Paul based on the time frame and context of dialog.
In Acts 20, after leaving Miletus, Paul sets sail for Jerusalem, in hopes to “reach Jerusalem, if possible, by the day of Pentecost (Shavuot)” (Acts 20:16). Paul reaches Jerusalem (we assume) by Pentecost (first week of the month of Sivan), but has evidently been in contact with a corpse and thus must undergo the seven day purification ritual as prescribed by the Torah (see my Footnote), and in the process underwrites the concluding offerings for the Nazarite vows of four men in order to prove his faithfulness to Torah (and not for purposes of deception as some would have us think). This puts him in Jerusalem for at least a week or two at the minimum, bringing us up to the second or third week of Sivan.
During his time at the Temple, he is accused of bringing his “Gentile inclusion” theology too close to home when they assumed he had brought a non-Jew beyond the soreg of the Temple. This accusation causes him to be hauled off to the magistrates who hold him in custody until the next day when he appears before the Sanhedrin to plead his case. Paul didn’t fare well with the Sanhedrin and is taken back to the barracks to spare his life. He is held at least for a day, possibly two (depending on how you read the text) and from there is taken, during the night, towards Caesarea. They get as far as Antipatris, which is beyond the half-way point. When they have rested and daylight has come, Paul is taken by the cavalry the remainder of the distance to Caesarea.
Paul is kept under guard in Herod’s palace (23:35) until he is brought before Felix five days later (24:1). This brings us up to the last week of Sivan, possibly the first week of Tamuz. After hearing Paul, Felix adjourns him, wanting to wait for Lysias (presumably the Roman commander who had Paul sent to Felix initially) to come and give his report of the events which have brought Paul to this point.
Here is where it gets vague. “Several days later” Felix sends for Paul to hear him speak about faith in Messiah Yeshua (24:24). This is a very ambiguous chronological reference. Depending on what all was happening politically, Paul stayed in his confines anywhere from a week to months, while he waited on Lysias to shed his more pressing matters in Jerusalem and make the trek to Caesarea in order to testify about this “Jewish trouble-maker,” whom I am sure he was in no great hurry to redeem. So… I’m guessing that Paul’s appearance before Felix for this event could have happened anywhere from the middle of Tamuz to some time in Elul.
This is where I am making a small leap. Based on the themes of Paul’s sermon while speaking to Felix (besides it obviously being a message he could use to hear at any point), I am thinking it was closer to (if not actually within) the month of Elul, and Paul’s three-point sermon of righteousness, self-control and the impending judgment would have been a perfect lead in to Rosh Hashanah and Yom Kippur, calling Felix to re-assess his ways and do t’shuva before the books of Life were once more closed. Felix, starts sweating bullets and dismisses Paul and his convicting message. May we see his mistake and take heed ourselves, lest we enter the Court of the King of Kings unprepared in this season.
1 I am assuming Paul had come into contact with a corpse, based on the phrase “Paul…purified himself” (21:26), combined with “When the seven days were nearly over” (21:27), which I can only assume is in reference to the prescribed purification rite of cleansing one from contact with a corpse (Numbers 19:11ff).