You're wrong, actually. In the old days it was the religion of the father that determined the religion of children not the mother. That was later changed because when Jewish settlements would be attacked the men and boys would be killed and the women and girls carried off into slavery. They changed it to the woman's line because they knew the women would be sure to survive any war. If they had continued to make the male lineage the requirement for Judaism then Judaism would have died out long ago.