"The question before the human race is, whether the God of nature shall govern the world by his own laws, or whether priests and kings shall rule it by fictitious miracles?"
"Indeed, Mr. Jefferson, what could be invented to debase the ancient Christianism which Greeks, Romans, Hebrews and Christian factions, above all the Catholics, have not fraudulently imposed upon the public? Miracles after miracles have rolled down in torrents."
"The United States of America have exhibited, perhaps, the first example of governments erected on the simple principles of nature; and if men are now sufficiently enlightened to disabuse themselves of artifice, imposture, hypocrisy, and superstition, they will consider this event as an era in their history. Although the detail of the formation of the American governments is at present little known or regarded either in Europe or in America, it may hereafter become an object of curiosity. It will never be pretended that any persons employed in that service had interviews with the gods, or were in any degree under the influence of Heaven, more than those at work upon ships or houses, or laboring in merchandise or agriculture; it will forever be acknowledged that these governments were contrived merely by the use of reason and the senses."
That’s an endorsement of morality and the idea of religion. I agree with John Adams on that. But what he is advocating there is not the same as a stipulation that every citizen has to have one particular set of religious values, which is what a theistic society does.
The problem with truth, even the truth as set out in the Bible, is that it has to be interpreted. In fact, that is what Christians spend their whole lives doing - interpreting and applying the idea of God and what that means to them as individuals. The problem is that what God wants for you at a particular point in time is not neccesarily what he wants for someone else, but people forget that. They think that the revelation that they have recieved is so wonderful and blindingly obvious that anyone who doesn’t “get it” must not be a “proper” Christian (as if there were any other requirement than God’s hand being upon you). Anyway, once you start saying that you have got God “right”, it follows that everyone who says differently must have God “wrong”, and therefore their opinions are of less (or no) value. That’s a dangerous idea to have in the body politic of a democratic system.