Point being SCOTUS can even agree with itself. It has the power of the gun, which means we may care about its position, but hardly that it is right.
We may be bound legally by their ruling, but that is simply a matter of law and tradition. The Supreme Court does not itself have a constitutional mandate to decide on the meaning of the constitution and the constitutionality of laws. It started when a chief justice decided that is what the court was going to do in 1803, and everyone went along with it.
The concepts of case law and judicial review are simply traditions of our legal system.
The constitutional clause in question says that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof..." That to me seems to say the government shouldn't be screwing with it one way or the other.
I do disagree with your statement that Chief Justice Marshall 'decided that is what the court was going to do', as the everyone in the ratification debate, including the Anti-Federalists, believed that federal courts could find a statue to be unconstitutional. Marbury v. Madison was the first to exercise that power. The 1796 case of Hylton v. United States, under Chief Justice Ellsworth, shows that judicial review for constitutionality was not new to Marshall.
My earlier comment was "after Edwards v. Aguillard settled that teaching creationism in public schools was not constitutional". I believe this is clearly in the context of the post-Marbury v. Madison tradition of the last 200 years.
Your followup comment was "There are no constitutional restrictions on what can be taught in schools." As you are coming from a different tradition, and a distinctly minority and non-influential one, I think you would have been more clear had you written "The Constitution doesn't say the Supreme Court has the right to decide what can be taught in schools."
Otherwise, we were under the incorrect belief that summarizing Edwards v. Aguillard would be enough to show that your statement was incorrect.
Under the US legal tradition since the early 1960s, schools are not part of a free exercise of religion. See Engel v. Vitale, Abington School District v. Schempp, and related cases dealing with prayer in school for the logic.
It also doesn't seem clear to me how setting up a curriculum (a legal act, after all) can't be covered by that text, unless you want to go back and argue it is only concerned with preventing a church becoming literally "established" like the Anglican Church is in England.
I disagree. The judicial branch, within which the Supreme Court is established as the paramount actor, has the Constitutional role of resolving all cases and controversies arising under the Constitution and laws of the United States, which cases and controversies often, in their resolution, require determining the meaning of the Constitution and laws of the United States.
"Edwards v. Aguillard, 482 U.S. 578 (1987) was a U.S. Supreme Court case concerning the constitutionality of teaching creationism. The Court ruled that a Louisiana law requiring that creation science be taught in public schools, along with evolution, violated the Establishment Clause of the First Amendment because the law was specifically intended to advance a particular religion."
In the spirit of the OP's article, let me say that I wholeheartedly agree with you, but you might want to look at this from another perspective... ;-D