Latin is to the Catholic Church what the Declaration of Independence is to America. As President Lincoln said:
When we celebrate the Fourth of July, Lincoln told his listeners in Chicago, we celebrate the founders, "our fathers and grandfathers," those "iron men...But after we have done this we have not yet reached the whole. There is something else connected with it. We have besides these men—descended by blood from our ancestors—among us perhaps half our people who are not descendants at all of these men, they are men who have come from Europe—German, Irish, French and Scandinavian—...finding themselves our equals in all things. If they look back through this history to trace their connection with those days by blood, they find they have none, they cannot carry themselves back into that glorious epoch and make themselves feel they are part of us, but when they look through that old Declaration of Independence they find that those old men say that ’We hold these truths to be self-evident, that all men are created equal,’ and then they feel that the moral sentiment taught in that day evidences their relation to those men, that it is the father of all moral principle in them, and that they have a right to claim it as though they were blood of the blood, and flesh of the flesh of the men who wrote that Declaration, and so they are."
The comparison is so appropriate, as Lincoln's words capture the spiritual meaning of your words:
"Latin is to the Catholic Church what the Declaration of Independence is to America".