When referring to gerim and the process of giyur, the terms are often translated as ‘converts’ and ‘conversion’. Probably because nobody knows what the hell a ‘proselyte’ is. Had I not grown up on the Blackman Mishnayoth, I’d think it’s the opposite of an electrolyte, but I digress.
The term ‘conversion’ implies a radical break, and rather instantaneous. The paradigm ‘conversion experience’, for William James, the father of comparative religion, is Saul of Tarsus (aka St. Paul) beholding the vision of Jesus on the road to Damascus. He’s not the same after the experience.
If the issue were belief, then I suppose a conversion can happen fairly instantaneously. I don’t believe in Jesus. BAM! Now I believe in Jesus. By the yidden, the process is far different. One can experience an epiphany and decide to believe in the Torah and the Covenant, but for us that’s just the beginning.
I think Chazal were onto something when they referred to ‘Jews by Choice’ as ‘gerim’. The term literally means ‘immigrants’ (not ‘strangers’ as is often translated). The process of becoming Jewish is very similar to the process of immigrating which, incidentally, is a highly traumatic experience. It means learning a new language, culture, attitudes, laws, you name it. Granted, there is a ‘moment’ when the legal (read: Halakhic) status of the ger changes from non-Jew to Jew, but the process is really much longer than that.
To illustrate, compare the process of giyur to the process of naturalization. In the US, the process of naturalization culminates with conferral of legal citizenship by the court. In halakha, a beit din confers the status of ‘ben brit’ upon the ger. In both, there is an agreement to protect and uphold the Law (Constitution/Torah) of the nation, and a binding of one’s fate with the fate of that nation. The parallels here are stronger than parallels to other types of religious conversion.
I find this line of reasoning helpful when trying to explain a) why being Jewish isn’t simply a matter of ‘personal choice’ or ‘identification’; citizenship (or enfranchisement) is a real, legal construct which has broad consensus and must be conferred by a representative body of the absorbing nation; b) why Orthodoxy doesn’t accept heterodox conversions.
Another implication is that nowadays, the baal teshuvah experience can also be a process akin to immigration, just without the issues of personal status (kinda like making Aliyah). Thinking about it in this way can help identify what some of the attractions and difficulties of taking on a Halakhic lifestyle involves.