(JTA) — It was unseasonably cold on Sunday morning when thousands of rabbis crowded on risers in front of Chabad-Lubavitch headquarters in Brooklyn to snap a photograph.

The group photo is a signature moment during any gathering of the Orthodox movement, allowing the movement to create a visual record of its growth: Unique among Hasidic movements, Chabad is known for sending rabbis and their wives to far-flung locations around the globe to minister to local Jews, regardless of denomination or beliefs. (A picture taken at a smaller gathering of Chabad rabbis in Kazakhstan last year netted...