It is also a very important letter for piecing together a chronology of the New Testament, and of the life of Paul. But that is not an easy task. There are lots of different data points which it is non-trivial to bring together. To give a simple example, in Galatians 2:1, Paul says "Fourteen years later I went up again to Jerusalem". Fourteen years later than what? Perhaps, fourteen years later than the visit to Jerusalem mentioned in Galatians 1:18. Or, perhaps fourteen years later than his conversion, which he dated the Galatians 1:18 visit as being three years later than. I have in my lap at present a commentary which on page 44 states the latter, then on page 50 states the former without seeming to be aware of the self-contradiction!
One of the difficult questions is whether Galatians 2:1-10 is an account of the same "Jerusalem council" as in Acts 15. On the face of it, this seems quite likely:
- It is a meeting in Jerusalem,
- occasioned by a controversy over the role of the law of Moses in salvation,
- and in particular circumcision
- involving Paul, Barnabas, Peter and James,
- which gave a decisive verdict in favour of a circumcision-free, law-free gospel.
- The Galatians 2 meeting appears to have been private and unofficial between a few apostles, whereas the Acts 15 one was fairly public and official involving many more leaders of the church.
- The Jerusalem council laid down some guidelines that Gentiles should not indulge in particular acts that would inflame Jewish sensitivities; whereas in Galatians Paul only reports an exhortation to help the poor - which the Jerusalem council's letter does not mention. (There are various other apparent dissimilarities which are arguments from silence and are therefore weak, but in this case we have the council's letter in totality, so this argument from silence is significant). Likewise, the Judaisers might have been expected to use the council's prohibitions against these inflammations of Jewish sensibilities, distorting them to make them into absolute laws for all Gentile Christians for all times - but Paul never tackles this argument, which suggests it was not being made.
- One border-line is-it-an-argument-from-silence difference: in Galatians Paul states that he went to Jerusalem because of a revelation, whereas in Acts 15 the church in Antioch determined after discussion to send him. (I could conceive that both could be true). But if Galatians 2 is in fact reporting events of Paul's Jerusalem visit in Acts 11:27-30, this fits in well: the trigger then was a revelation through the prophet Agabus, and that Acts visit was a visit in part for poor relief, which in Galatians 2:10 Paul reports as being a matter on his heart at that time.
- In Galatians, Paul makes no explicit mention of any official pronouncement on the question. This is again an argument from silence, but I'd assert a significant one. Why would he only speak of private agreement, when after the Jerusalem council an official letter was written that should have settled the matter once and for all? Such an argument would be weighty and powerful - final, indeed. If the Jerusalem council had taken place by the time Paul wrote Galatians, it is strange that he speaks of it only in such a guarded, round-about way when its verdict was so helpful to his case. The Judaisers were clearly saying "the Jerusalem apostles agree with us, not Paul" - why would Paul fail to appeal to their public pronouncement to the contrary, and only testify of a private agreement?