Separation of church and State
I do not believe in the creed professed by the Jewish Church, by the Roman Church, by the Greek Church, by the Turkish Church, by the Protestant Church, nor by any church that I know of. My own mind is my own church.
Thomas Paine

If you ever wonder why American constitutional scholars believe that there should be a separation of church and state, just take a look here at the thoughts of the people who were the "Founding Fathers":

I have examined all the known superstitions of the Word, and I do not find in our particular superstition of Christianity one redeeming feature. They are all alike, founded on fables and mythology. Millions of innocent men, women and children, since the introduction of Christianity, have been burnt, tortured, fined and imprisoned. What has been the effect of this coercion? To make one half the world fools and the other half hypocrites; to support roguery and error all over the world ...
Thomas Jefferson