This stuff doesn't actually map neatly to who's most "observant".
A Jew accidentally eats some pork.
So he goes to a series of rabbis and says, "I accidentally ate some pork--what's the halacha on this? Is God angry with me?"
The Conservative rabbi says: What's "accidentally"?
The Reform rabbi says: What's "halacha"?
The Reconstructionist rabbi says: What's "God"?
that's prob a good encapsulation of how the "big four" Jewish movements think abt each other, but.
And part of that was attempting to get rid of a lot of Jewish practice that was "outdated" or, basically, too "ethnic" seeming.
myjewishlearning.com/article/ask-th…
Most Reconstructionist Jews aren't traditional theists.
On the other hand, Judaism isn't defined by belief, or even theology. It's not a religion--it's a civilization with a distinctive religion.
But not because God says so--because this is our civilization, because we're not just tossing out tradition.
I love Reform Judaism (although I don't love a lot of things about classical Reform Judaism, I love what it is now).