That is true, but how many generations ago was that? 80? In each line of descent, for every "Jew-by-birth" man who married a non-Jewish woman, the line would become "gentile", as none of their descendants would be Jewish. Over 80 generations, the likelihood of an unbroken matrilineal string of halakhic Jews, while not mathematically impossible, is exceedingly unlikely. Because "Jewishness" ceased to matter to them, and they freely intermarried.
that means Conversion is not accurate
How so? If someone were (unknowingly) Jewish, and "converted" to Judaism, the end result would be the same -- that person would now be Jewish. The fact that their conversion was unnecessary doesn't really matter.
That's the thing Malakhi, there is no way of knowing that because there is no documentation to back it up? Jacob had 12 Sons which I believe are the Original 12 tribes of Israel, the apostles are part of this tribe, This is GOD'S chosen people, it does not say biblically that over time through inter-marraige he does not consider them Chosen any longer right?
How many generations did the apostles children and there children and so on through generations did or did not marry Jews?
We don't know that?
You cannot determine Conversion on who is truly a Gentile unless they have claimed Atheism.
I think you are coming up with who is Jewish by history standards of the 20th Century...