The Democrat Party has become the greatest internal threat to America’s security, prosperity, and founding principles.

Kevin is right on the money.  One of Adolph Hitler's first actions in office was to ban all political parties except the National Socialists.  I don't think he equated political disagreement as mental illness (you know, HDS); Stalin did that ("sluggish schizophrenia"), but he criminalized it.  David, is that what the Founding Fathers had in mind when they wrote the Constitution?

 Is today's radical, law breaking, government shutting down, illegal alien embracing DemocRAT party what the Founfing Fathers had in mind when they wrote the Constitution?

Almost certainly. Or at least partialy.

Many founders were quite "radical".  They broke many laws,  there was essentially no such thing as illegal immigration, and Jefferson argued there should be a revolution to replace government every 25 years. 

Is today's MAGA Constitution-ignoring, human rights-destroying, pedo rapist-embracing, illegal war-exploiting Republican party what the Founders had in mind?

Re "illegal immigration," it's interesting to note that evenbin the 19th century, there were movements to keep immigrants out of the country altogether. The only successful effort, though, was the 1889 (?) Act that specifically excluded Chinese. You built our railroads, now get the fuck out.

So I ask myself what were the Founders' intentions, and what have the people said, informally or formally. It appears that the Founders actively wanted and encouraged immigration. That makes sense, as America was still a mostly empty land (ignoring the indigenous tribes, of course). I originally thought that the American public has always supported immigration as well. But the more I read, the more I see that that was not the case at all. In particular, ethnic/national groups that had just gotten off the boat themselves vehemently opposed the entry of subsequent groups.

Race hatred and in general, hatred of the "other" is, despite our national mythology, baked deeply into the American psyche. That's why it's a core element of Republican doctrine today.