I think the wording is quite clear. What is there to not understand?
I think this wording is also quite clear:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.-
So that means slavery was abolished in 1776 right? That's what the words say don't they? The words are quite clear. All men have equal rights.
So does history demonstrate that those words mean that? No, they demonstrate quite the opposite. They don't really mean that at all.
I'm arguing that the prohibition against religious tests doesn't mean what people think either. Just because the words are plain doesn't mean that the interpretation of them is actually correct.