According to a recent poll the three least religious states inthe U.S. are: 1. Vermont 2. New Hampshire, and 3. Maine, followed by Massachussetts and Rhode Island.
Though I will say, there are pockets, at least in Maine where people are VERY religious, but I guess they are drowned out by all of the heathens in Southern and Central Maine.
http://www.religionnews.com/2013/02/14/photo-slideshow-gallups-least-religious-states-of-2012/ (http://www.religionnews.com/2013/02/14/photo-slideshow-gallups-least-religious-states-of-2012/)
In my experience, "very" religious Mainers are
1) French-Canadians, not Mainers
and
2) Catholic, not members of an actual religion.