At Sinai on Shavuot, the souls of all future Jews by birth and by conversion accepted the Torah. When any of these Jewish souls by choice are not warmly welcomed into the Jewish people a terrible sin is done
Unlike Buddhism, Christianity and Islam, Judaism does not have much of a missionary impulse. That is why there are so few Jews in the world. Mormons, who very actively seek converts, already outnumber Jews even though they have been around less than 200 years compared to more than 3,500 years for Jews.
Judaism lacks a strong missionary impulse because Judaism is a pluralistic religion. Judaism teaches that the Jewish way is right for us, but good people in other religions also have a place in the world to come.
Correct behavior in society is more important than correct beliefs about God. Thus, while Jews welcome non-Jews to join us, we do not have a urgent motive to ‘enlighten’ or ‘save’ them.
Lacking the missionary impulse of more universalistic religions, Jews react to potential converts in varied ways, ranging from wariness to encouragement. Practical community concerns guided many of out Sages.
Some like Rabbi Helbo said that converts are an irritation like an itch, a sore or a scab. Perhaps Rabbi Helbo felt that the enthusiasm and idealistic expectations of converts irritated too many born Jews, who take their Jewishness much more casually.
Or maybe he agreed with Rabbi Isaac who said “Evil after evil comes upon those who receive converts”. Both these Rabbis lived in the early 4th century when the Church was vociferously attacking pagans who choose to become Jews rather than Christians. Perhaps they feared Christian anti-Semitism if Jews were to openly welcome converts.
On the other hand, Rabbi Simon ben Lakish proclaimed that a convert is more beloved to God than all the Jews who stood at Sinai. This seems rather extreme. Perhaps he was reacting to those who claimed Jewishness was in the noble genes of their ancestors.
Equally amazing were Rabbi Eleazar ben Pedat and Rabbi Yohanan who both taught that the forced exile of the Jewish people among the Gentiles, was really a God given opportunity to influence Gentiles to become Jewish.
Some Rabbis tried to test the sincerity of potential converts by making great demands of time and effort from them. Opposing this Rabbi Yohanan advises that you should push potential converts away with your left hand and draw them close with your right hand.
Since most people are right handed if you actually push away more than one of two you are being too negative.
Rashi, the greatest of our Bible commentators, taught that Jews started seeking converts from the very beginning, when he interpreted a verse that states that Abraham made souls in Haran, to mean that Abraham and Sarah made converts.
Most important, the Talmud (Sanhedrin 99b) condemns those who push potential converts away by relating that Isaac and Jacob pushed away Timna the sister of Lotan who wanted to become Jewish. She then married a son of Esau. One of her descendants was Amalek who attacked Israel shortly after they escaped from Egypt.
If, instead of being pushed away, Timna had become Jewish, Amalek would have been on our side, and not one of our enemies. A more practical view is hard to imagine.
Indeed, Rabbi Yohanan says the Jews were oppressed and enslaved in Egypt because Abraham didn’t try to influence some captives that he rescued to become Jewish. Even failing to encourage potential converts is wrong according to Rabbi Yohanan.
Thus several of our Rabbis felt that discouraging converts in the past had brought troubles upon us. These are practical, not theological, reasons to welcome converts and not to push away those who might be interested.
Rabbis today should welcome potential converts and not discourage them. We may not be saving souls, but we should not be making future enemies by rejecting people who want to be Jewish.
The negative, suspicious, and often sinful treatment of Russian Jews by some Israeli Orthodox courts is an example of what not to do.