Want to know how "those people" think? Ask them.
Not their opponents. To begin with, those opponents might be ignorant. Might think all politically-conservative US Protestants are Fundamentalists; or be unaware that liberals aren't socialists.
More to the point, "those people" have direct access to their own thoughts; their own way of seeing the world; their own feelings. They might not be entirely truthful with you (or with themselves) -- but their opponents might not be, either.
And at worst, you'll be able to observe how they talk.