Assalamu alaikum dear brother,
Yeah, I have asked this question to christians but they didn't give a satisfactory answer!
In other places in the NT, where Jesus prefers Jews over Gentiles- I asked it about too. They said whoever believes in Jesus is son of Abraham, thus a Jew!
But unfortunately they don't have this chance in Revelations because it says- "12000 from the tribe of ....." and so on. This totally exposes the bible as racist and man-made hoax.
The number however, 144000, seems familiar. As a hadith says there are 124000 prophets who came to earth for different nations.
This is the farthest I could explain. How can I explain a man made book anyway?
Peace