I agree that the Calvinist formulations are very simple to grasp and in that sense are "systematic". The Word, on the other hand is enigmatic. I stick with the Word, because it gives everlasting life; but if you want crude simplicity, Calvin is it.
I also agree that most Protestants are not Calvinist. A good friend of mine is a Calvinist pastor and he certainly made the distinctions clear for me and my wife.
Then no doubt you will be able to explain my tagline.