#1 - their general attitudes toward organized religion ranged from tepid to hostile.
#2 - their nominal denominations notwithstanding, their personal beliefs ranged from Unitarian Christianity to deism.
With six people, that's a bit of a simplification. Franklin, say, was quite supportive of religion, and was noted for donating to build the first synagogue in Philadelphia, along with many other religious buildings.
George Will calls the book "well documented, exuberantly argued, and quite persuasive," and I have to agree. He also calls it a "polemic", which is also quite accurate. At times, Allen practically says, "I wish I could shove that quote from Madison under Pat Robertson's nose and watch him plotz."
Anyway, that polemical edge sometimes rubbed me a little raw, but otherwise it's quite an enjoyable read, even if I think she spends more time finding the sharpest daggers among the founders' quotes than presenting a complete picture.
Some of the info is fairly well-known -- at least to people who know that the closest thing to Christianity you find in the Constitution is the phrase 'year of our lord' -- but other sections were interesting surprises.
I guess I was most surprised by Washington. Allen blames the standard American mythology version of Washington on Parson Weems' best-selling if highly inaccurate biography. In reality, although a Virginian gentleman of his class could hardly do other than be an upstanding member of the Episcopal church, he was once upbraided by Reverend James Abercrombie for absenting himself when communion was offered:
I considered it my duty in a sermon on Public Worship, to state the unhappy tendency of example, particularly of those in elevated stations who uniformly turned their backs upon the celebration of the Lord's Supper. I acknowledge the remark was intended for the President; and as such he received it. A few days after, in conversation, I believe, with a Senator of the United States, he told me he had dined the day before with the President, who, in the course of conversation at the table, said that, on the previous Sunday, he had received a very just rebuke from the pulpit for always leaving the church before the administration of the sacrament; that he honored the preacher for his integrity and candor; that he had never sufficiently considered the influence of his example, and that he would not again give cause for the repetition of the reproof; and that, as he had never been a communicant, were he to become one then, it would be imputed to an ostentatious display of religious zeal, arising altogether from his elevated station. Accordingly, he never afterwards came on the morning of sacrament Sunday, though at other times he was a constant attendant in the morning.
Whoa, don't mess with the President. Washington didn't say much at all about his private beliefs, but the ministers of the churches he attended agree that he was not a professing Christian.
Adams' religion speaks for most of them: "For the last Year or two I have devoted my self to this kind of [theological] study [numerous books mentioned] Romances all! I have learned nothing of importance to me, for they have made no change in my moral or religious Creed, which has for 50 or 60 years been contained in four short words "Be just and good."
Adams didn't get much out of Plato, either. The two things he learned were that Franklin's idea of exempting Husbandmen and Mariners from War service was borrowed from Plato, and that Sneezing cures Hickups.