Hi Douglas. Nice to see you.
Regarding: "Fortunately not ALL of Christianity believes this..."
Unfortunately though, traditional(Constantinian) Christianity teaches that outsiders are not saved. There may be a few sects or (many?) individuals who disagree with that...but they are labeled heretics/apostates of the "true" church if differing viewpoints are expressed.
I know that God guarantee's all of Judah and Israel will be saved. I also know that God says that you must believe that Jesus was the Christ and that he died for humanity:
Act 4:12 Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved.
As for the details, God will work it out. I think that is what Revelation chapter 20 describes.