Under normal circumstances, the Jewish community does not seek converts

One of the most basic principles of Judaism is that different people have different souls - in other words, if you weren't born Jewish you don't have a Jewish soul and thus have no business trying to convert.

This knowledge comes from the deep dark recesses of kaballa, and rests heavily on the belief in reincarnation - not something that those in the know are very keen to distribute among the uninitiated, since it conflicts with many of the more mundane practices of practical Judaic lore.

This is the combination of reasons why, when confronted with would be converts, the various religious authorities are both unsympathetic and inscrutable. In fact, I know of cases in Israel where people who wanted to convert in order to marry to Jewish people were asked by the rabbis to separate from their partners for up to two years, to test the strength of their conviction and to make sure it isn't just a romantic gesture on their part. The religious studies are rigorous, too.

I have to say, though, that the few people I know who did convert to Judaism and chose to lead a religious life in Israel are some of the biggest fanatics and zealots I ever met. Makes a weird kind of sense, I guess.

The Jews did proselytize, at least before this was outlawed when the Roman Empire became Christian. At the start of the Christian era, 10%-12% of the Roman Empire were Jews, which is hard to explain unless there were a lot of converts. Once the restrictions against Jewish proselytization were lifted, doing this never really caught on again. Also, for whatever historical worth it might have, here is a quote from the New Testament, Matthew 23:15

Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell than yourselves.

It is true that, currently, people are discouraged from converting to Judaism. While part of it might be because of kaballaistic mysticism, most of it is due to the fact that Judaism holds that you don't have to convert (or at least, convert fully) to lead a righteous life. All of the religious laws that religious Jews are supposed to follow aren't considered universal laws for everyone, but laws for people who fall under a special covenant with God, either through voluntary conversion, or by being a Jew through matrilineal descent (the children of a Jewish woman are considered Jewish for religious purposes). For people who don't fall under this covenant, the only things required to lead a righteous life come from the Noachide covenant:

• Don't lie, steal, murder, and so on.
• Love your neighbor, take care of widows and orphans, and so on.
• Worship Jehovah, not any of the false gods, and certainly don't commit idolatry.
• Don't eat meat that has any blood left in it. (This was a rule handed down to Noah after the flood, and thus presumably binding on all humans).

Religious Jews have to follow that, plus a whole lot more; and once you convert to Judaism, you can't change your mind, you're under the new covenant for life. So why convert to Judaism when you don't have to? Also, the Jewish religious leaders don't want someone converting and then doing a half-hearted job of it.

So, when someone expresses interest in converting to Judaism, they are discouraged. If they seem real serious, then they begin on intensive religious study. This serves three purposes:

1. It further weeds out anyone who isn't serious.
2. It lets people know what they're in for, so they can still back out before they fully convert and there's no turning back. "I'd have to what?! Um, on second thought, I think I'll stay a pagan."
3. The person will know all of the various rules that they have to follow once they complete their conversion.