And since the Pilgrim religion was based on the church goers voting, conscience became a huge thing. People were expected to vote their conscience, and their votes became church doctrine.
What this did was create a religion that could evolve based on the values of its members. And it did.
While the 1620 Pilgrims were... not awesome on issues like slavery and sexism, they made a religion that could evolve along with the beliefs of the people.