The folks at Jerusalem are not talking about salvation, which is the first step in the Christian life. They are covering the continuance into progressive sanctification, into walking the walk. And that is about works, in the journey into spiritual maturity.
Of course, for Circumcision or Uncircumsision, salvation is NOT by the heuristic algebra:
Faith + Works => Salvation
as some erroneous theologies would insist. Salvation's benefit is by this arrangement:
Faith + Salvation => Works
"And I heard a voice from heaven saying unto me, Write, Blessed are the dead which die in the Lord from henceforth: Yea, saith the Spirit, that they may rest from their labours; and their works do follow them" (Rev. 14:13)
"For we must all appear before the judgment seat of Christ; that every one may receive the things done in his body, according to that he hath done, whether it be good or bad" (2 Cor. 5:10)
This is about rewards, about furthering His interests as His bondslaves. It is about making. inducting, and instructing disciple-followers.
Both sides agree, for the most part, that we are 'saved' by Faith.
Where we differ is it appears that one group says we HAVE to have 'works' to KEEP our Salvation.
The other side says, "Nope; we're KEPT by Faith as well.
When I was a youngun the local Presbyterian Church had at least one Crucifix..
What happened since then..
This was in New Zealand, a British Commonwealth country so maybe the US is different ???