Yes I saw that story about this era where Christians really pushed to make us a Christian nation.
They even put in god we trust on the dollar
In the U.S., we are by definition a secular nation -- there was considerable debate among the Founding Fathers about the entire god issue-- and the constitution is quite secular.
One can argue far better that having come from theocracies themselves the Founding Fathers were very much aware of the dangers of blending religion and government. Even if they personally believed -- they purposely ratified a constitution that was totally secular in nature (and intent). They clearly did not wish to eradicate religion which is why they enacted a muzzle on government to keep religious expression free. However, the result of this by definition means the gov't cannot exalt one religion over another. Keep
Christianity in culture, whether or not
Christianity is dominant or not, but do not allow the government to assert it or any other religion over the other. The only way to do that is to be neutral on the issue of religion at all. As the country does become more diversified and embraces more religious beliefs (including none) the Constitution is designed to evolve to include those concerns. The Founding Fathers would, I believe, note their legal design has worked quite well.