The argument against the TMT is that it would be built on sacred ground, essentially for religious reasons. Isn't that an establishment of religion and, therefore, in violation of the first amendment?
No. This is not, in the words of the First Amendment, about passing a law that prescribes a particular religion or impedes the free exercise thereof. This is a dispute about the usage of land. Scientist want to use it to build a telescope. A group of native Hawaiians object on the grounds that the land has historic and spiritual significance. IMHO, both sides have standing, and I hope they work something out that preserves both of their interests.