Ophiucus, read what you wrote! You wrote the meaning of the Constitution (mostly) correctly, but you totally misunderstood what you wrote. To my knowledge at no time in history has the congress passed a law "respecting an establishment of religion or prohibiting the free exercise thereof". It has not happened. Therefore, the 1st Amendment protection of religion, intended to protect the states and the people from the federal government, has never been usurped by federal lawmakers. It has been usurped, many times, by unelected federal judges who have imposed their wills and ideologies on the states and the people.
... the US attempted to establish a secular government with a nonsecular people.
I'm not so sure about that, Ophiucus. One of the first things the first congress did was to establish a daily, Christian prayer. Certainly the first congress would been in a better position to know the intent of the constitution than you or I. Justice Story, in his Commentaries, disputes the notion that the original intent was to create a secular nation. The notion that this is a secular nation is new-fangled, worming its way into our "laws" via judiciary usurpation within the last 40 or 50 years.
If a legislature passes a law banning the teaching of evolution OR requiring the teaching of a religious precept like creation of ID, it is violating the First Amendment by both requiring the teaching of one sect's religious views and by favoring one Christian sect over others.