)
The essence of conversion is the convert’s acceptance of the Jewish people’s grand vision –actualized through Torah and mitzvot –and the wish to be a part of it. Therefore, if potential converts say they are unwilling to accept a particular mitzva as a matter of principle, we do not convert them. If someone converts them anyway, the conversion is invalid. Since the Reform and Conservative movements do not believe all the mitzvot must be observed, conversions performed under their auspices are not valid. One practical consequence is that if a man converted through one of these movements, married a Jewish woman and then left her, she may remarry even without obtaining a get.
In contrast, when converts fundamentally accept Torah and mitzvot upon themselves, their conversion is valid even if they are still unaware of many of the mitzvot, because they are prepared to keep everything. Furthermore, even if they are worried during conversion that they may not be able to keep all the mitzvot – whether because temptation might be overwhelming, or because they might have to work on the Shabbat in order to make a living – the conversion is valid, since fundamentally they want to observe the mitzvot. Of course, if a potential convert has no intention of keeping the mitzvot and lies to the court, the conversion is invalid.
The question arises as to the status of someone who wishes to convert with the intention of living a traditional lifestyle of partial observance, rather than an Orthodox lifestyle of complete observance. Many authorities are strict and maintain that such a person should not be converted; only someone who is planning to keep all the mitzvot – including Shabbat, the laws of family purity, the laws of kashrut, and the recitation of prayers and blessings – may be converted. (Even according to this opinion, if converts sincerely accepted all the mitzvot and a court agreed to convert them, but after the conversion their commitment weakened and they ceased being observant, they are still considered Jewish. Just as a non-observant Jew remains Jewish, so too a convert who converted properly and then stopped being observant remains Jewish.)
Others are more lenient and argue that if converts intend to live a traditional lifestyle, as long as their general approach to Torah and mitzvot is positive, they should be accepted. First, they are interested in observing some mitzvot, so there is a chance that over the course of time they will begin to observe them all. Second, they do intend to keep many mitzvot, which shows they do sincerely want to take part in the Jewish people's mission. Traditional Jews often observe interpersonal mitzvot; the laws of kashrut, and the rites of circumcision, marriage, burial, and mourning. So even if converts do not intend to observe Shabbat fully, they may be planning to take time off from work, to light Shabbat candles and recite Kiddush, and to celebrate the holidays. Converts planning to serve in the IDF, will also be observing the mitzvot connected to settling and defending the Land , which the Sages tell us are the equivalent of all the other mitzvot put together.
In practice, if a conversion court decides to follow the lenient opinion and accept a traditional-minded convert, the conversion is valid even according to the strict opinion.
