Im not fully sure if I understand what your asking but
There was still a point to have Israyl, it was SUPPOSED to be a light to the world, so all the other nations would see how blessed they were and say, "dang, I wanna be like that, how do I do it?" You know then all would eventually turn to Yahweh, but of course Israyl went astray.
Ezekiyl 18:21, "But if the wicked will turn from all his sins that he has committed, and keep all My statutes, and do that which is Lawful and right, then he will surely live; he will not die."
Even now we still have to turn from our sin after receiving the blood of Messiah, IMO Yahshua's blood covered all the sins even of those prior to the actual Sacrifice, as the blood of animals could never really cleanse sin.
And the stranger who dosent worship Yahweh, IDK, my guess is they would be in trouble?