But after that the kindness and love of God our Saviour toward man appeared,
Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost;
Which he shed on us abundantly through Jesus Christ our Saviour;
That being justified by his grace, we should be made heirs according to the hope of eternal life. (Titus 3:4-7)
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.