Reformed Offlian
Master Poster
For some values of "plenty". The studies I've seen, including the one used in wikipedia, typically identify a fraction of 4-5%.There are plenty of religious non-Christians in the USA. They don't all live in the traditional Christian states. In fact, in many cases they might wish to avoid them. Therefore you would expect some bias away from the utterly predictable stats this report gives.
Religion in the United States - Wikipedia
Popular imagination tends to exaggerate vastly the number of practising Muslims here (it's around 1%). All indications I see are: around 90% of folks in the U.S. who identify as religious at all, identify as some form of Christian. Significant differences in the degree of religiosity from state to state are overwhelmingly likely to stem from differences in the number of people who identify as Christian. Other religions just aren't big enough to move the needle that much.