Not as odd as one might think, even if one assumes that the mindset of a warp propulsion engineer tends towards the materialistic rather than the spiritual. A rabbi isn't a priest, but a scholar and a teacher. Their roles in the religious life of a modern practicing Jew do bear a strong resemblance to that of a Protestant pastor or minister, and they are ordained, but the intellectual life is distinctly different.

It's also worth noting that in our world, Russian Jews of the 21st century tend to identify as such far more as a matter of ethnic identity rather than religious faith or cultural heritage. There's some renewal of interest in the latter components of late, which is encouraged and facilitated by the Chabad, although Sergei Roshenko is manifestly not Hasidic.

One last note: Minsk, in Belarus, is where Worf specifically mentions having grown up, and a quick Google shows Ivanova's birthplace as Saint Petersburg, but, personally? I'd revise either of these, or chalk it up to the exceedingly efficient travel of the late 24th century, for the awesomeness of Worf and Ivanova as childhood friends and latter-day drinking buddies :D.

"Mathematics brought rigor to economics. Unfortunately, it also brought mortis."
- Kenneth Boulding