When did Paul become an apostle?

Paul became an apostle when he converted to Christianity. His epistles provide some evidence that can help provide a year for his conversion.

Soon after his conversion to Christianity, Paul spent 3 years in Damascus, but escaped the city when the governor under Aretas, king of the Nabateans from 9 BCE to 40 CE, had a garrison deployed to arrest him because of his Christian activities (2 Corinthians 11:32-3). This information gives us a first-cut estimate for the start of the Pauline period. There is no reason at this stage to assume that the escape should have occurred near the end of the king's reign, a somewhat improbable coincidence, but if it did then Paul's conversion was no later than the year 36.

In his Epistle to the Galatians, Paul said that after his conversion, he travelled to Arabia, then Damascus (bypassing Jerusalem), Jerusalem, then Syria and Cilicia, and back to Jerusalem (Galatians 1:16-2:1). At some stage after the last visit to Jerusalem, he appears to have visited Antioch with Peter. He must have spent 3 years in Damascus, 14 years in Syria and Cilicia, and indeterminate periods in the other centres. Therefore, his conversion would have been at least 18 to 20 years before he wrote Galations.

We may be able to establish an approximate year for Galatians, because Galatians, 1 Corinthians, 2 Corinthians and Romans all mention a collection that Paul was expending considerable effort and political capital to raise for the poor of Jerusalem. The best known explanation for this collection would be the Great Famine of 44 to 48. This means that Galatians, 1 Corinthians and 2 Corinthians were written during the period 44 to 48, with Romans during the same 4 year period, or soon afterwards. In 1 Corinthians, Paul said that he had already commanded the Galatians to contribute. I believe that Paul first raised the subject with the Galatians in his epistle to them, so Galatians would be the first of the series and written not much later than the year 44.

We know from Paul's adventure in Damascus, that his conversion could not have been later than 36 CE, and could have been much earlier. If Galatians was written in 44 CE or very soon afterwards, and if his conversion was 18 to 20 years before this, then Paul's conversion could have been as early as the year 24. If so, we could need to revise Paul's relationship with the traditional crucifixion date of 30 or 33 CE.