“Or is God the God of Jews only? Is He not the God of Gentiles also? Yes, of Gentiles also, since indeed God who will justify the circumcised by faith and the uncircumcised through faith is one.” – apostle Paul (Romans 3:29 – 30)

P/S:

Let us note that He will “justify” both the “Circumcised” and the “uncircumcised” via “faith”.

Also, for the

(i) Jewish Believers

Circumcision & customs of Moses could still be valid:

“take them and purify yourself along with them, and pay their expenses so that they may shave their heads; and all will know that there is nothing to the things which they have been told about you, but that you yourself also walk orderly, keeping the Law.” (Acts 21:24)

Because apostle Paul was told by the “Jewish believers” above to ‘prove the claim wrong’ by doing the above.

What was this false ‘claim’?
That apostle Paul taught the “Jewish believers” (not Gentile believers, a distinction clearly mentioned in these verses) to “forsake the Law of Moses, even circumcision” as these verses show:

“And when they heard it they began glorifying God; and they said to him, “You see, brother, how many thousands there are among the Jews of those who have believed, and they are all zealous for the Law;

and they have been told about you, that you are teaching all the Jews who are among the Gentiles to forsake Moses, telling them not to circumcise their children nor to walk according to the customs.” (Acts 21:20 – 21)

(ii) Gentile Believers

In the same breath, we see that the “Gentile Believers” are required to keep these four aspects only from the “custom/law of Moses” part (‘subject of the matter’ in these set of verses), the distinction being very clearly mentioned in the verse below too (agreeing to the ‘previous letter’ endorsed by all elders, apostles & the Holy Spirit of God in Acts 15:22 – 29)

““But concerning the Gentiles who have believed, we wrote, having decided that they should abstain from meat sacrificed to idols and from blood and from what is strangled and from fornication.” (Acts 21:25)

*A distinction according to the “role” (Jewish believers vs Gentile Believers) in this aspect is clearly mentioned in Scripture as the verses above prove.