SLC is a definite exception. In the other cities there would be no problem avoiding church related influence in your daily life (although this is entirely relative as plenty of our laws are based on and still created according to christian views). I think there is very little difference between the midwestern metropolises and the coastal metropolises on this point (and I've now lived in all three areas). SF and NYC are a definite cut above all others, but not by a large margin.

Your dig on the midwest is uncalled for, by the way. I've lived most of my life in Minneapolis and spent four years in Boston. I found Boston to be significantly more racist, politically corrupt, and conservative (in the resistant to change and backward looking senses) than Minneapolis. For base simplifications of American political views, the urban / rural comparison is infinitely better than the coast / interior state comparison. In fact the latter is just 100% wrong. There are plenty of religious wingnuts here in the Bay Area just like anywhere else.

you are the media you consume.