[Alexander Rubin]

It's not a facet of the Progressive movement. It's a facet of the Jewish assimilation movement of the 19th century, that's been touched by democratic socialism and heavily influenced by it in the early 20s. It helped spawn the Progressive movement (or the New Left), but it's not a facet.

Simplified, it's a facet of what happens when a progressive religious movement (which it was) meets the modern world, tries to adapt, and is too focussed on the progressive/adaption part and not strong enough to survive as a viable religious movement as a result.

[Inyokern]

It's not a facet of the Progressive movement. It's a facet of the Jewish assimilation movement of the 19th century, that's been touched by democratic socialism and heavily influenced by it in the early 20s.

The two are not mutually exclusive.

It helped spawn the Progressive movement (or the New Left), but it's not a facet.

I disagree with that statement. You are giving Reform Judaism credit for original thought, which it does not deserve.

Reform Judaism is not a leader, it is a follower. Leftwing ideas are not spawned there, they are merely assimilated. Leftwing ideas typically originated among university intellectuals and Democratic Party activists and eventually filter down to Reform Judaism.