Hi there, Haigan!
I referred to this document in one of the political blogs in which you've been contending that the U.S. is a Constitutional REPUBLIC, and not a democracy. It occurred to me after that you may not notice that post, and I wanted to make sure you don't miss out!
I found an informative document, published by the U.S. government itself, explaining the nature of the American political system. Seeing as it is coming directly from the source, I'm sure you will agree that the veracity of the contents is incontestable.
The direct link to the document is: https://www.uscis.gov/system/files_force/USCIS/files/Government_and_You_handouts.pdf
However, in case you are pressed for time I'll do you the courtesy of pasting the contents of the first page below.
I hope you find the provided information helpful in understanding the commonly known nature of the government under which you live, so that in future you won't make yourself appear foolish by denying the most fundamental aspect of it.
I wish you well.
~ Warren