Maggie's Farm

Rev Graham is a full-blooded Christian. As such, he is likely to view Islam with alarm because of its strident anti-Christian message and because he genuinely believes that Islam diverts souls from God. He may hold a somewhat similar view of Judaism and Buddhism among others. Being a Theist, I would probably also make Rev Graham's list of those who are being diverted from God.
I am sure that, at the National Day of Prayer, Rev Graham would have acknowledged his own beliefs without insulting anyone else's.
The Founding Fathers were a motley religious crew. George Washington was careful in public to speak of Providence rather than a specific God. Thomas Jefferson did not make public professions of Christian faith and Ben Franklin -- well, yes, look him up. We've elected 4 Unitarian presidents.
As for religious groups and terror in the name of their religion -- the Latter Day Saints established a community that bordered on cultism in Utah. The Mountain Meadows massacre was a dreadful event and there were others. That part of LDS history is long over but it happened. We also had some ugly 17th-century events involving heresy charges among various Christian sects.