First, out Founding Fathers, while they were Christian, didn't set out to create a Christian nation. They had the good sense to guarantee the freedom to choose and to practice religion freely. Otherwise we would run the risk of being governed by religious zealots like the taliban or the Saudis, etc.
Second, I have a hard time figuring out how those who use scripture to support their opinions decide which verses they should cherry pick from, considering there is quite a bit of contradictory direction in there. Or should we really kill people for eating shellfish or shaving their beards? After all, the good book says they are an abomination and should be killed. I hate to disagree with the word of God, but that seems a bit harsh to me.
Here's one of my favorites.
"You have heard that it was said, 'An eye for an eye, and a tooth for a tooth.' But I tell you, do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also. And if someone wants to sue you and take your tunic, let him have your cloak as well. If someone forces you to go one mile, go with him two miles. Give to the one who asks you, and do not turn away from the one who wants to borrow from you."
It kind of makes you wonder if Rev. King or Mr. Gandhi were on to something.