So, you believe this is an acknowledgment of some sort for a command for Gentiles to learn the Law in local Synagogues? Why? Please quote the text and show to us the grammar that would seem to indicate such, coupled with an analysis as to where you think that's stated or implied in the grammar of those passages?
What I see is James, an apostle to Israel, not to Gentiles, was simply saying that the Law of Moses is indeed taught in every province. So what? Notice also in that context that only four of the commands in the Law were handed over to Paul for him to uphold among his Gentile and Jewish converts, with not one statement I can find that said Gentiles were to attend local Synagogues to learn the Law; especially given that they who believed in Christ Jesus as Messiah were not welcome in Jewish Synagogues given that the vast majority of Synagogue leadership disbelieved Messiah had yet come.
Do you take the position that the four things lists in Acts 15:19-21 contain exhaustive list of everything that is required of mature believers or do you take the position that there are obviously other laws that Gentiles should follow? It is contradictory to treat it as being an exhaustive list for mature believers in order to limit which ways Gentiles should follow Christ while also treating it as being a non-exhaustive list by taking the position that there are obviously other ways that Gentiles should follow Christ. It was not given as an exhaustive list for mature believers but as a list intended to avoid making things too difficult for new believers coming to faith, which they justified in verse 21 with the expectation that Gentiles would continue to learn about how to Christ's example of practicing Judaism by hearing Moses taught every Sabbath in the synagogues. Jews attend synagogues every Sabbath in part to continue to learn about how to practice Judaism, so this would have been the most natural way for Gentiles to continue to learn about how to do that. A Gentile would be extremely confused if they wanted to become a follower of Christ's example of practicing Judaism while wanting nothing to do with following over 99% (609/613) of what he taught.
In Acts 15:21, it starts with the word "For", so there is a grammatical connection between point that Peter was making in that verse and what he said in verses 19-20. I don't see what other point Peter could have been making in verse 21 that is relevant to verses 19-20 if not that Peter was giving Gentiles a starting point and expecting them to continue to learn about how to follow Christ's example of practicing Judaism. Gentiles who convert to Judaism are not expected to have all 613 laws memorized on day one, but rather there is a starting point and a process of continuing to learn over time. How do you think the point that Peter was making in verse 21 is relevant to verses 19-20?
Again, Jewish believers in Jesus were able to form their own synagogues where they were the leaders and where Gentiles would be welcome to continue to learn about how to practice Judaism.
For backing to what I'm saying here, let's go on to another exchange between James and Paul:
Acts 21:21
And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children, neither to walk after the customs.
Given that chapter 21 is at a time long after that meeting in chapter 15 of Acts, thus laying down the death blow to any idea that Gentile believers were expected to learn the Mosaic Law. After all, dare we read the above verse for what it says, Paul was teaching even the Jews under his ministry to "forsake Moses," not to follow him and the Law he was inspired to write down for Israel and Israel alone.
Acts 6:13-14 and they set up false witnesses who said, “This man never ceases to speak words against this holy place and the law, 14 for we have heard him say that this Jesus of Nazareth will destroy this place and will change the customs that Moses delivered to us.”
It directly states that false witnesses accused Stephen as speaking against this holy plan and the Torah and of speaking about changing the customs of Moses that had been delivered to them, which means that Stephen had not actually been doing that. Similarly, in Acts 21:20-24, they planned to take steps to disprove false rumors that Paul had been teaching to forsake the Torah. They were rejoicing that tens of thousands of Jews were coming to faith in Jesus who were all zealous for the Torah, which is in accordance with Titus 2:14, where Jesus gave himself to redeem us from all lawlessness and to purify for himself a people of his own possession who are zealous for doing good works, so Jews coming to faith in Jesus were not ceasing to practice Judaism but were becoming zealous for it. This means that there was a period between the resurrection of Jesus and the inclusion of Gentiles in Acts 10 that is estimate to be around 7-15 years during which all Christians were Torah observant Jews who practiced Judaism, that Christianity at its origin was the sect of Judaism that recognized Jesus as the Messiah, and that Gentiles who were joining this religion were converting to Judaism. In Acts 24:14, Paul testified that according to The Way, which they called a sect, he continue to worship the God of their fathers, believing everything laid down by the Torah and written in the Prophets, and the religion of which The Way is a sect is Judaism.
In Ephesians 2:12-19, Gentiles were at one time separated from Christ, alienated from Israel and strangers to the covenants of promise, having no hope and without God in this world, which is in accordance with Gentiles at one time not being doers of the Torah, but through faith in Christ all of that is no longer true in that Gentiles are no longer strangers or aliens but are fellow citizens of Israel along the saints in the household of God, which is in accordance with Gentiles becoming doers of the Torah. So Gentiles who were joining this religion were also becoming joined to Israel and the Torah being for Israel means that it is also for Gentiles.
So, you're in a Synagogue that teaches Orthodox Judaism? As an Israeli I was raised with Torah, and have long since walked away from it given that we are not dead to the Law. Like Paul, I too teach my fellow Jews who are believers to forsake the Mosaic Law.
MM
Indeed. In Romans 7:21-8:7, Paul said that he delighted in obeying the Law of God in contrast with the law of sin that held him captive, he said that he served the Law of God with his mind in contrast with serving the law of sin with his flesh, he said that the Law of the Spirit has freed us from the law of sin and death, and he contrasted those who walk in the Spirit with those who have minds set on the flesh who are enemies of God who refuse to submit to the Law of God, so it should at least be word considering whether we need to die to the law of sin in order to be free to obey the Law of God or whether we need to die to the Law of God in order to be free to obey the law of sin.
In Deuteronomy 13, the way that God instructed His children to determine that someone is a false prophet is if they speak against obeying the Torah, so if you agree that Paul was a servant of God, then you should be opposed to you interpreting as teaching to forsake the Torah, and if you think that Paul should be interpreted as teaching to forsake the Torah, then you should be opposed to you considering him to be a servant of God, but either way followers of Christ should follow the example of how to walk in obedience to the Torah that he set for his followers to follow (1 Peter 2:21-22).