In Seeking Sister wives one family is not religious at all, they choose the lifestyle.
The other couple were asked to leave their place of worship when they told the congregation they wanted a polygamous
lifestyle and the 3rd couple I believe were once Mormons, but since mainstream Mormons no longer accept polygamous
marriages, they don’t belong. The one couple said they were told if they repented of their sin and chose the traditional marriage, they could retutn to
their “synagogue”, but from my understanding they were not Jewish.
Perhaps Messianic or Noahides.