its complicated because jews simply dont want to pollute the notion of the family of israel who was a prophet, judaism isnt just a religion, its a concept of blood line, a race, which existed from ancient times, there are many atheist jews, so why arnt they thrown out of judaism??
the reason is simple, judaism isnt just about religion, its about blood
there is a jewish family out there in israel who migrated from russia, but the jewish rabbis dont declare them being the jews, because they think they arnt original jewish of the jew tribe, infact the russian family is providing all the evidence how they have been jews from a long lineage their ancestors have followed judaism and they are jews of the jew tribe, but still they arnt been decreed to be the original jews
such is the condition of judaism