Verse 21, it's plain as day.
20 Instead we should write to them, telling them to abstain from food polluted by idols, from sexual immorality, from the meat of strangled animals and from blood.
((((((((((21 For the law of Moses has been preached in every city from the earliest times and is read in the synagogues on every Sabbath.”))))))))
That's called context.
No, it isn't plain as day and, no, that isn't called context. You stated that Peter said, "that the Gentiles can learn the law as their faith grows," but that is not at all what is said. First, there is no mention of growing in faith. Second, knowledge of the law is very clearly limited to four things, as the immediate context states:
Act 15:19 Therefore my judgment is that we should not trouble those of the Gentiles who turn to God,
Act 15:20 but should write to them to abstain from the
things polluted by idols, and from
sexual immorality, and from
what has been strangled, and from
blood. (ESV)
That's it. Four things from the law for the Gentile believers to follow, and those were written from the council of Jerusalem converts to Gentile converts without any mention of them being from the Law of Moses.
The most likely reason for verse 21 is that the Jews knew about keeping those things, because they kept so much more, as they had been taught them for a very long time in the synagogues. Gentile believers wouldn't have known those things, so it was likely that in order to keep Jewish converts, who likely kept the ceremonial laws for some time after, from suffering offense.
You can't combine what happened in Acts 10 with Acts 15. It's two totally separate events years apart.
Acts 15 is directly related to Galatians.
As you like to say, "context." You also have to take what I, and others, say in context. I was quoting Acts 15:8-9, which is speaking of what happened in Acts 10, although it could also be
Act 15:8 And God, who knows the heart, bore witness to them, by giving them the Holy Spirit just as he did to us,
Act 15:9 and he made no distinction between us and them, having cleansed their hearts by faith. (ESV)
Act 10:44 While Peter was still saying these things, the Holy Spirit fell on all who heard the word.
Act 10:45 And the believers from among the circumcised who had come with Peter were amazed, because the gift of the Holy Spirit was poured out even on the Gentiles.
Act 10:46 For they were hearing them speaking in tongues and extolling God. Then Peter declared,
Act 10:47 “Can anyone withhold water for baptizing these people, who have received the Holy Spirit just as we have?” (ESV)
Which is recounted in chapter 11:
Act 11:15 As I began to speak, the Holy Spirit fell on them just as on us at the beginning.
Act 11:16 And I remembered the word of the Lord, how he said, ‘John baptized with water, but you will be baptized with the Holy Spirit.’
Act 11:17 If then God gave the same gift to them as he gave to us when we believed in the Lord Jesus Christ, who was I that I could stand in God's way?” (ESV)
The topic debated was about 2 things and 2 things only. You can't add to it to fit your narrative.
1) one sect claimed you had to follow the law FIRST in order to enter the faith.
You haven't shown that to be the case; it doesn't say.
Act 15:1 But some men came down from Judea and were teaching
the brothers, “Unless you are circumcised according to the custom of Moses, you cannot be saved.” (ESV)
Not that it matters whether it was first or after becoming believers, the whole point was that following the law, or certain parts of the law, was a burden even the Jews couldn't bear, according to Peter.
2) You didn't have to follow the law FIRST to enter the faith.
Except that was not what was debated. It was that they didn't have to follow the law at all, apart from four things, right?
Act 15:11 "But we believe that we will be saved through the grace of the Lord Jesus, just as they will.” (ESV)
The Gentiles were saved but nothing more was to trouble them
in regards to the law, or at least parts of the law, than four things.
The Decision that came from Acts 15.
AND
2) The rest of the Law of Moses is taught every week on the sabbath to educate them.
No, that is not at all what is stated.
Act 15:21
For from ancient generations Moses has had in every city those who proclaim him, for he is read every Sabbath in the synagogues.” (ESV)
That is clearly speaking of Jews. Besides, believers largely met in house churches on the first day of the week. This is probably particularly true of Gentile converts, who may or may not have gone to a synagogue on the Sabbath. They likely didn't as they weren't converts to Judaism.
In simple terms,
Converts did not need to know and practice the law before entering the faith, just the idolatry and sexual immorality that went along with pagan worship,
If one has to practice certain things
prior to entering the faith, then that can be nothing but works salvation, which is directly opposed to salvation by grace through faith. That is a different gospel, and one Peter disposes of in verse 11, right? If you deny that you are teaching salvation by works, what do you mean by your statement? Maybe you would like to reword it, especially since the four things were for
after Gentiles had converted.
then learn, just as we do now, after they enter the faith.
That is the only context you can
correctly extrapolate from Acts 15. Those are the only two things debated.
Context
We can learn about the law, and we should, but how it is applicable to believers, and what parts are applicable, is more tricky and still debated.