It's true. Atheist don't have to be democrats, but I'm not sure about the other way around.
The goodness of God and Jesus don't seem to mesh with the dems message lately.
Au contraire, most of the libs I've known have been religious in the traditional sense, and most far-left individuals have been adherents of "alternative" religions which mix Buddhism, animism and eco-feminism in a weird metaphysical melange.