My acquaintance was confused. He said, "just because he is a Leftie doesn't mean that he doesn't believe in God."
I think that is exactly what it means. Leftism is the religion of people who don't believe in God.
By the same token, being a Leftist can mean that even though a person may be Jewish by blood and culture, they are not Jewish by religion.
As a footnote (something we all know), Leftism is nothing more than humanism (i.e., the belief that humans are the center of the universe, not God. And that humans are capable of creating Eden on Earth and capable of bringing about our own salvation).
Leftism/humanism obscures and even denies that it is cut from the same cloth as Satan when he declared that he would be "AS the Most High."
Leftists/humanists seem unaware that they do have a god who directs their beliefs and actions. They forget about their forefather.
What you posit is what a number of people born of the line with ancestry to Jacob, who have had their minds poisoned by the talmud call Jewish religion. Which is nothing but mans opinion about the Torah, or the Pentateuch, the LITERAL Word of the Creator to the Hebrews through Moses.
The best way to think of it is like the US Constitution as the Supreme law of the land (Torah), yet lawyers and legislators follow the commentary of the Courts (Talmud). I cannot distinguish between the examples.