Levite
Higher and Higher
A conservative Jewish friend told me this is one of the main reasons proselytizing isn't done more. Being threatened with death, imprisonment, or various other terrorist punishments is a fresh memory and still a reality in some parts of the world. It's a shame, to put it mildly. I'd love proselytic Jews in my area. Of course, I've read the other reasons here and understand the lack of a need for it, but if nothing else, forging friendships and understanding is valuable.
Actually, proselytism by Jews was continuously prohibited under dire penalties in most countries in Europe, North Africa, the Middle East, and the Persian sphere of influence until the nineteenth century, and in some of those places, it is still prohibited-- all the way through since Roman times.
There is some indication to support the idea that the prohibitions came first, and the justifications on our side later, but nonetheless, there seem to be strong indications that proselytisim was self-prohibited in Judaism as early as Tannaitic times (the period of the Mishnah), which would pre-date Roman proscription of Jewish proselytization by a couple of centuries.
There are some today who argue that, the dangers largely being past, we ought to re-consider our stance, and begin to actively proselytize. But I think today we can justify continuing to prohibit proselytizing simply by understanding how unpleasant, intrusive, and arrogant it is-- which we know, all too often being the victims of attempts at Christian proselytization.