Writing on Jewschool, David Kelsey points out what would be the biggest stumbling block to recruiting new ba'alei teshuva – if the BTs knew about it. For the most part, potential BTs do not know. I think it's time to change that.
Simply put, if your mother did not go to the mikva and immerse following her menstrual period immediately before you were conceived, you are what is known in halakha as a ben (or bat) nida. And you are, according to halakha, blemished, tainted, and far more likely to do evil than a Jew born to a mother who did immerse. Therefore, halakha advises that untainted Jews not marry you – or your descendants.
That's right – Judaism has a caste system and BTs are down near the bottom of it.
Several great rabbis have ruled that ben nida does not apply to a BTs who comport themselves in a good (subservient) way. (Perhaps the most normal of these rulings comes from the Steipler Gaon, who points out that even the most haredi of haredi families must statistically have a blemish like this in its background and that, since the taint is never removed, the taint must still remain and exist in every one of us. Therefore, we don't need to worry about who is and who is not a ben nida.) But that has not stopped wide swaths of the haredi world from forbidding their children to marry BTs, and even children of BTs.
I first heard of this issue early in my contact with Chabad. I heard about it from other BTs, more experienced than I, usually as a warning – Don't even think about marrying Rivkie or Chanie. Her mother went to the mikva and yours probably did not, so you can't marry her.
Chabad rabbis would spin this problem by saying that a BT's children could marry into a 'non-tainted' family. And there was always the occasional exception to the rule, handy for pointing out the 'openness' of Chabad. Of course, that exception nearly always involved a BT with a lot of money or a 'untainted' girl with serious mental or physical problems.
No matter how you slice it, Orthodoxy has a caste system based on a metaphysical taint that can never be removed. How many Jews would become Orthodox if this were widely known? How many non-Orthodox philanthropists would fund Orthodox institutions?
A lot fewer than do so today would be my guess.
Wouldn't it be nice to see how many that would be?