The cases I’ve looked over don’t address the issue of the 10th amendment regarding religion… I scanned lemon v kurtzman, but found nothing there.

I think that it just wasn’t believed to be an issue, I think that goes back to Marbury v Madison where the Supreme Court declared itself the supreme arbitor and interpretor of the constitution (Thomas Jefferson disagreed, by the way, he felt it should be the people’s representatives in Congress who decided).

With Marbury v Madison, I think we saw the death of the 10th amendment.