Why would someone want to become a Jew? There are a number of reasons.
1. Many people – perhaps the bulk – convert to Judaism because of marriage. Whether for familial acceptance or a desire to unite the family under one religion, non-Jewish partners do convert. Rabbis make sure they say their spiel on ensuring the person is converting out of love of Judaism and not for any other reason (such as marriage), but that’s all they can do. And even if someone is converting because of marriage, and not because his/her heart is in it, rabbis probably recognize that it’s better for the children in any case to be raised by two Jewish parents, even if one is not thoroughly Jewish. The statistics of the affects of mixed-faith marriages with Jews – with Judaism eventually being forgotten – alarm rabbis enough that they permit this to happen. (Why am I talking about rabbis? More about this on Friday.)
2. Some people actually do fall in love with Judaism, and desire to become a part of the religion, the people, the history. People find fulfillment in Judaism. This is not a new phenomenon, as the Talmud comments on conversion indicate: evidently some people were lukewarm in their dedication and devotion, but others, although born non-Jewish, feel fulfilled in Judaism. Conversion in Judaism thrives in the West, where it is common for people to leave the faith of their birth for another religion, so people feel more open and daring to join Judaism. (In the East, leaving the religion of one’s birth is a far trickier matter.)
There is a theory among some Jews that those with a nefesh yehudi (Jewish soul) are drawn to Judaism. Most are born into Judaism. Others must find it and join it. A nefesh is Jewish (yehudi) when it was present at Mt. Sinai as God gave His revelation. All Jewish souls participated in that event. Some souls were not born into a Jewish body, so the body must change its status to agree with the soul. Thus, there is no such as a conversion to Judaism but rather the recognition of having a nefesh yehudi and bringing oneself into compliance with that. (This is somewhat similar to the theory in Islam that there is no conversion to Islam – it’s a reversion because all souls are born Muslim.)
But one cannot simply declare oneself as Jewish. Almost all forms of Judaism – Reform, Reconstructionist, Conservative, Orthodox, Conservadox – have a process a person needs to go through in order to officially convert to Judaism or to be recognized as a Jew.